{"id":3210,"date":"2023-11-02T17:20:10","date_gmt":"2023-11-02T09:20:10","guid":{"rendered":"https:\/\/xinchewhd.com.cn\/?p=3210"},"modified":"2023-11-02T17:20:10","modified_gmt":"2023-11-02T09:20:10","slug":"20%e4%b8%aa%e6%8f%90%e5%8d%87%e6%95%88%e7%8e%87%e7%9a%84js%e7%ae%80%e5%86%99%e6%8a%80%e5%b7%a7%ef%bc%8c%e5%91%8a%e5%88%ab%e5%b1%8e%e5%b1%b1%ef%bc%81","status":"publish","type":"post","link":"https:\/\/xinchewhd.com.cn\/index.php\/vue\/20%e4%b8%aa%e6%8f%90%e5%8d%87%e6%95%88%e7%8e%87%e7%9a%84js%e7%ae%80%e5%86%99%e6%8a%80%e5%b7%a7%ef%bc%8c%e5%91%8a%e5%88%ab%e5%b1%8e%e5%b1%b1%ef%bc%81\/","title":{"rendered":"20\u4e2a\u63d0\u5347\u6548\u7387\u7684JS\u7b80\u5199\u6280\u5de7\uff0c\u544a\u522b\u5c4e\u5c71\uff01"},"content":{"rendered":"
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JavaScript \u4e2d\u6709\u5f88\u591a\u7b80\u5199\u6280\u5de7\uff0c\u53ef\u4ee5\u7f29\u77ed\u4ee3\u7801\u957f\u5ea6\u3001\u51cf\u5c11\u5197\u4f59\uff0c\u5e76\u4e14\u63d0\u9ad8\u4ee3\u7801\u7684\u53ef\u8bfb\u6027\u548c\u53ef\u7ef4\u62a4\u6027\u3002\u672c\u6587\u5c06\u4ecb\u7ecd 20 \u4e2a\u63d0\u5347\u6548\u7387\u7684 JS \u7b80\u5199\u6280\u5de7\uff0c\u52a9\u4f60\u544a\u522b\u5c4e\u5c71\uff0c\u8f7b\u677e\u7f16\u5199\u4f18\u96c5\u7684\u4ee3\u7801\uff01<\/p>\n

\u79fb\u9664\u6570\u7ec4\u5047\u503c<\/h2>\n

\u53ef\u4ee5\u4f7f\u7528 filter()<\/code> \u7ed3\u5408 Boolean<\/code> \u6765\u7b80\u5316\u79fb\u9664\u6570\u7ec4\u5047\u503c\u64cd\u4f5c\u3002\u5047\u503c\u6307\u7684\u662f\u5728\u6761\u4ef6\u5224\u65ad\u4e2d\u88ab\u89c6\u4e3a false<\/code> \u7684\u503c\uff0c\u4f8b\u5982 null<\/code>\u3001undefined<\/code>\u3001\u7a7a\u5b57\u7b26\u4e32\uff08\"\"<\/code> \u6216 ''<\/code>\uff09\u30010\u3001NaN<\/code> \u548c false<\/code>\u3002<\/p>\n

\u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n

<\/span><\/span><\/span><\/span> <\/span><\/section>
let<\/span> arr =<\/span> [<\/span>12<\/span>,<\/span> null<\/span>,<\/span> 0<\/span>,<\/span> 'xyz'<\/span>,<\/span> null<\/span>,<\/span> -<\/span>25<\/span>,<\/span> NaN<\/span>,<\/span> ''<\/span>,<\/span> undefined<\/span>,<\/span> 0.5<\/span>,<\/span> false<\/span>]<\/span>;<\/span><\/span><\/span><\/span>let<\/span> filterArray =<\/span> arr.<\/span>filter<\/span>(<\/span>value =><\/span> {<\/span><\/span>    if<\/span>(<\/span>value)<\/span> {<\/span><\/span>      return<\/span> value<\/span>    }<\/span>;<\/span><\/span>}<\/span>)<\/span>;<\/span> <\/span>\/\/ [12, 'xyz', -25, 0.5]<\/span><\/span><\/code><\/pre>\n
\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
let<\/span> arr =<\/span> [<\/span>12<\/span>,<\/span> null<\/span>,<\/span> 0<\/span>,<\/span> 'xyz'<\/span>,<\/span> null<\/span>,<\/span> -<\/span>25<\/span>,<\/span> NaN<\/span>,<\/span> ''<\/span>,<\/span> undefined<\/span>,<\/span> 0.5<\/span>,<\/span> false<\/span>]<\/span>;<\/span><\/span><\/span>let<\/span> filterArray =<\/span> arr.<\/span>filter<\/span>(<\/span>value =><\/span> Boolean(<\/span>value)<\/span>)<\/span>;<\/span> \/\/ [12, 'xyz', -25, 0.5]<\/span><\/span><\/code><\/pre>\n
\u66f4\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
let<\/span> arr =<\/span> [<\/span>12<\/span>,<\/span> null<\/span>,<\/span> 0<\/span>,<\/span> 'xyz'<\/span>,<\/span> null<\/span>,<\/span> -<\/span>25<\/span>,<\/span> NaN<\/span>,<\/span> ''<\/span>,<\/span> undefined<\/span>,<\/span> 0.5<\/span>,<\/span> false<\/span>]<\/span>;<\/span><\/span><\/span>let<\/span> filterArray =<\/span> arr.<\/span>filter<\/span>(<\/span>Boolean)<\/span>;<\/span> \/\/ [12, 'xyz', -25, 0.5]<\/span><\/span><\/code><\/pre>\n
Boolean<\/code> \u662f JavaScript \u7684\u5185\u7f6e\u6784\u9020\u51fd\u6570\uff0c\u901a\u8fc7\u4f20\u9012\u4e00\u4e2a\u503c\u7ed9\u5b83\uff0c\u53ef\u4ee5\u5c06\u8be5\u503c\u8f6c\u6362\u4e3a\u5e03\u5c14\u503c\u3002\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0cBoolean<\/code> \u6784\u9020\u51fd\u6570\u4f5c\u4e3a\u56de\u8c03\u51fd\u6570\u4f20\u9012\u7ed9 filter()<\/code> \u65b9\u6cd5\uff0c\u56e0\u6b64\u4f1a\u5c06\u6bcf\u4e2a\u6570\u7ec4\u5143\u7d20\u8f6c\u6362\u4e3a\u5e03\u5c14\u503c\u3002\u53ea\u6709\u8f6c\u6362\u7ed3\u679c\u4e3a\u771f\u503c\u7684\u5143\u7d20\u624d\u4f1a\u4fdd\u7559\u5728\u65b0\u6570\u7ec4\u4e2d\u3002<\/p>\n
\u6ce8\u610f\uff1a\u8fd9\u79cd\u65b9\u5f0f\u4f1a\u5c06 0 \u4e5f\u8fc7\u6ee4\u6389\uff0c\u5982\u679c\u4e0d\u9700\u8981\u8fc7\u6ee4 0\uff0c\u9700\u8981\u8fdb\u884c\u989d\u5916\u7684\u5224\u65ad\u3002<\/p>\n
\u6570\u7ec4\u67e5\u627e<\/h2>\n
\u5f53\u5bf9\u6570\u7ec4\u8fdb\u884c\u67e5\u627e\u65f6\uff0cindexOf()<\/code>\u7528\u4e8e\u83b7\u53d6\u67e5\u627e\u9879\u7684\u4f4d\u7f6e\u3002\u5982\u679c\u672a\u627e\u5230\u8be5\u9879\uff0c\u5219\u8fd4\u56de\u503c\u4e3a-1<\/code>\u3002\u5728JavaScript\u4e2d\uff0c0\u88ab\u89c6\u4e3afalse<\/code>\uff0c\u800c\u5927\u4e8e\u6216\u5c0f\u4e8e0\u7684\u6570\u5b57\u88ab\u89c6\u4e3atrue<\/code>\u3002\u56e0\u6b64\uff0c\u9700\u8981\u8fd9\u6837\u6765\u5199\uff1a<\/p>\n
\u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
if<\/span>(<\/span>arr.<\/span>indexOf<\/span>(<\/span>item)<\/span> ><\/span> -<\/span>1<\/span>)<\/span> {<\/span> <\/span><\/span>}<\/span><\/span><\/span>if<\/span>(<\/span>arr.<\/span>indexOf<\/span>(<\/span>item)<\/span> ===<\/span> -<\/span>1<\/span>)<\/span> {<\/span><\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
if<\/span>(<\/span>~<\/span>arr.<\/span>indexOf<\/span>(<\/span>item)<\/span>)<\/span> {<\/span><\/span><\/span>}<\/span><\/span><\/span>if<\/span>(<\/span>!<\/span>~<\/span>arr.<\/span>indexOf<\/span>(<\/span>item)<\/span>)<\/span> {<\/span><\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
\u4f4d\u975e\uff08~\uff09\u8fd0\u7b97\u7b26\u5bf9\u9664\u4e86-1\u4e4b\u5916\u7684\u4efb\u4f55\u503c\u90fd\u8fd4\u56de\u4e00\u4e2a\"\u771f\"\u503c\u3002\u5bf9\u5176\u8fdb\u884c\u53d6\u53cd\u5c31\u662f\u7b80\u5355\u5730\u4f7f\u7528!~<\/code>\u5373\u53ef\u3002\u53e6\u5916\uff0c\u4e5f\u53ef\u4ee5\u4f7f\u7528includes()<\/code>\u51fd\u6570\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
if<\/span>(<\/span>arr.<\/span>includes<\/span>(<\/span>item)<\/span>)<\/span> {<\/span><\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
\u7a7a\u503c\u5408\u5e76\u8fd0\u7b97\u7b26<\/h2>\n
\u7a7a\u503c\u5408\u5e76\u8fd0\u7b97\u7b26\uff08??<\/code>\uff09\u7528\u4e8e\u4e3a null<\/code> \u6216 undefined<\/code> \u7684\u53d8\u91cf\u63d0\u4f9b\u9ed8\u8ba4\u503c\u3002<\/p>\n
\u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
const<\/span> fetchUserData<\/span> =<\/span> (<\/span>)<\/span> =><\/span> {<\/span><\/span>\treturn<\/span> '\u524d\u7aef\u5145\u7535\u5b9d'<\/span>;<\/span><\/span>}<\/span>;<\/span><\/span><\/span>const<\/span> data =<\/span> fetchUserData<\/span>(<\/span>)<\/span>;<\/span><\/span>const<\/span> username =<\/span> data !==<\/span> null<\/span> &&<\/span> data !==<\/span> undefined<\/span> ?<\/span> data :<\/span> 'Guest'<\/span>;<\/span><\/span><\/span><\/code><\/pre>\n
\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
const<\/span> fetchUserData<\/span> =<\/span> (<\/span>)<\/span> =><\/span> {<\/span><\/span>\treturn<\/span> '\u524d\u7aef\u5145\u7535\u5b9d'<\/span>;<\/span><\/span>}<\/span>;<\/span><\/span><\/span>const<\/span> data =<\/span> fetchUserData<\/span>(<\/span>)<\/span>;<\/span><\/span>const<\/span> username =<\/span> data ??<\/span> 'CUGGZ'<\/span>;<\/span><\/span><\/code><\/pre>\n
\u9664\u6b64\u4e4b\u5916\uff0c\u8fd8\u6709\u4e00\u4e2a\u7a7a\u4f4d\u5408\u5e76\u8d4b\u503c\u8fd0\u7b97\u7b26\uff08??=<\/code>\uff09\uff0c\u7528\u4e8e\u5728\u53d8\u91cf\u4e3a\u7a7a\uff08null<\/code> \u6216 undefined<\/code>\uff09\u65f6\u8fdb\u884c\u8d4b\u503c\u64cd\u4f5c\u3002<\/p>\n
\u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
let<\/span> variable1 =<\/span> null<\/span>;<\/span><\/span>let<\/span> variable2 =<\/span> \"\u524d\u7aef\u5145\u7535\u5b9d\"<\/span>;<\/span><\/span><\/span>if<\/span> (<\/span>variable1 ===<\/span> null<\/span> ||<\/span> variable1 ===<\/span> undefined<\/span>)<\/span> {<\/span><\/span>  variable1 =<\/span> variable2;<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
let<\/span> variable1 =<\/span> null<\/span>;<\/span><\/span>let<\/span> variable2 =<\/span> \"\u524d\u7aef\u5145\u7535\u5b9d\"<\/span>;<\/span><\/span><\/span>variable1 ??=<\/span> variable2;<\/span><\/span><\/code><\/pre>\n
??=<\/code> \u7684\u5199\u6cd5\u66f4\u52a0\u7b80\u6d01\u548c\u6613\u8bfb\u3002\u5b83\u9996\u5148\u68c0\u67e5\u53d8\u91cf variable1<\/code> \u662f\u5426\u4e3a null<\/code> \u6216 undefined<\/code>\uff0c\u5982\u679c\u662f\uff0c\u5219\u5c06\u5b83\u8d4b\u503c\u4e3a variable2<\/code> \u7684\u503c\u3002\u5982\u679c variable1<\/code> \u5df2\u7ecf\u6709\u4e00\u4e2a\u975e\u7a7a\u7684\u503c\uff0c\u90a3\u4e48\u8d4b\u503c\u64cd\u4f5c\u5c31\u4e0d\u4f1a\u53d1\u751f\u3002<\/p>\n
\u903b\u8f91\u6216\u8d4b\u503c\u8fd0\u7b97\u7b26<\/h2>\n
\u903b\u8f91\u6216\u8d4b\u503c\u8fd0\u7b97\u7b26\uff08||=<\/code>\uff09\u7528\u4e8e\u4e3a\u53d8\u91cf\u5206\u914d\u9ed8\u8ba4\u503c\u3002<\/p>\n
\u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
let<\/span> count;<\/span><\/span>if<\/span> (<\/span>!<\/span>count)<\/span> {<\/span><\/span>  count =<\/span> 0<\/span>;<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
let<\/span> count;<\/span><\/span>count ||=<\/span> 0<\/span>;<\/span><\/span><\/code><\/pre>\n
\u5f53 count<\/code> \u4e3a\u5047\u503c\uff08\u4f8b\u5982 undefined\u3001null\u3001false\u30010\u3001NaN \u6216\u7a7a\u5b57\u7b26\u4e32\uff09\u65f6\uff0c\u903b\u8f91\u6216\u8d4b\u503c\u8fd0\u7b97\u7b26\u5c06 count<\/code> \u8d4b\u503c\u4e3a 0\u3002\u5426\u5219\uff0c\u5b83\u4f1a\u4fdd\u7559 count<\/code> \u7684\u539f\u59cb\u503c\u3002<\/p>\n
\u591a\u503c\u5339\u914d<\/h2>\n
\u5bf9\u4e8e\u591a\u4e2a\u503c\u7684\u5339\u914d\uff0c\u53ef\u4ee5\u5c06\u6240\u6709\u7684\u503c\u653e\u5165\u4e00\u4e2a\u6570\u7ec4\u4e2d\uff0c\u7136\u540e\u4f7f\u7528 indexOf(<\/code>) \u65b9\u6cd5\u8fdb\u884c\u68c0\u67e5\u3002indexOf() <\/code>\u65b9\u6cd5\u662f JavaScript \u6570\u7ec4\u7684\u4e00\u4e2a\u5185\u7f6e\u65b9\u6cd5\uff0c\u5b83\u7528\u4e8e\u8fd4\u56de\u6307\u5b9a\u5143\u7d20\u5728\u6570\u7ec4\u4e2d\u7b2c\u4e00\u6b21\u51fa\u73b0\u7684\u4f4d\u7f6e\u7d22\u5f15\u3002\u5982\u679c\u6570\u7ec4\u4e2d\u4e0d\u5b58\u5728\u8be5\u5143\u7d20\uff0c\u5219\u8fd4\u56de -1\u3002<\/p>\n
\u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
if<\/span> (<\/span>value ===<\/span> 1<\/span> ||<\/span> value ===<\/span> 'one'<\/span> ||<\/span> value ===<\/span> 2<\/span> ||<\/span> value ===<\/span> 'two'<\/span>)<\/span> {<\/span><\/span>  \/\/ ...<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
if<\/span> (<\/span>[<\/span>1<\/span>,<\/span> 'one'<\/span>,<\/span> 2<\/span>,<\/span> 'two'<\/span>]<\/span>.<\/span>indexOf<\/span>(<\/span>value)<\/span> >=<\/span> 0<\/span>)<\/span> {<\/span><\/span>   \/\/ ...<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
\u66f4\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
if<\/span> (<\/span>[<\/span>1<\/span>,<\/span> 'one'<\/span>,<\/span> 2<\/span>,<\/span> 'two'<\/span>]<\/span>.<\/span>includes<\/span>(<\/span>value)<\/span>)<\/span> {<\/span> <\/span>    \/\/ ...<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
\u4e09\u5143\u8868\u8fbe\u5f0f<\/h2>\n
\u4f7f\u7528\u4e09\u5143\u8868\u8fbe\u5f0f\u8868\u793a\u53ef\u4ee5\u7b80\u5316if...else<\/code>\u3002<\/p>\n
\u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
let<\/span> isAdmin;<\/span><\/span>if<\/span> (<\/span>user.<\/span>role ===<\/span> 'admin'<\/span>)<\/span> {<\/span><\/span>  isAdmin =<\/span> true<\/span>;<\/span><\/span>}<\/span> else<\/span> {<\/span><\/span>  isAdmin =<\/span> false<\/span>;<\/span><\/span>}<\/span><\/span><\/span><\/code><\/pre>\n
\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
const<\/span> isAdmin =<\/span> user.<\/span>role ===<\/span> 'admin'<\/span> ?<\/span> true<\/span> :<\/span> false<\/span>;<\/span><\/span><\/code><\/pre>\n
\u66f4\u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
const<\/span> isAdmin =<\/span> user.<\/span>role ===<\/span> 'admin'<\/span>;<\/span><\/span><\/code><\/pre>\n
\u77ed\u8def\u6c42\u503c<\/h2>\n
\u5f53\u5c06\u4e00\u4e2a\u53d8\u91cf\u7684\u503c\u8d4b\u7ed9\u53e6\u4e00\u4e2a\u53d8\u91cf\u65f6\uff0c\u53ef\u80fd\u5e0c\u671b\u786e\u4fdd\u6e90\u53d8\u91cf\u4e0d\u4e3a null\u3001undefined \u6216\u7a7a\u3002\u53ef\u4ee5\u7f16\u5199\u4e00\u4e2a\u5305\u542b\u591a\u4e2a\u6761\u4ef6\u7684\u957f if \u8bed\u53e5\uff0c\u6216\u8005\u4f7f\u7528\u77ed\u8def\u6c42\u503c\u6765\u7b80\u5316\u3002<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
if<\/span> (<\/span>variable1 !=<\/span>=<\/span> null<\/span> ||<\/span> variable1 !=<\/span>=<\/span> undefined ||<\/span> variable1 !=<\/span>=<\/span> '')<\/span> {<\/span><\/span>    let variable2 =<\/span> variable1;<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
\u4f7f\u7528\u77ed\u8def\u6c42\u503c\u7b80\u5316\u540e\u7684\u4ee3\u7801\u5982\u4e0b\uff1a<\/p>\n
<\/span><\/span><\/span><\/span> <\/span><\/section>
const<\/span> variable2 =<\/span> variable1 ||<\/span> 'new'<\/span>;<\/span><\/span><\/code><\/pre>\n
\u5bf9\u4e8e\u903b\u8f91\u6216\uff08||\uff09\u64cd\u4f5c\u7b26\uff0c\u4ee5\u4e0b\u503c\u88ab\u89c6\u4e3a\u5047\uff1a<\/p>\n
    \n
  • \n
    false<\/p>\n<\/li>\n
  • \n
    0<\/p>\n<\/li>\n
  • \n
    \u7a7a\u5b57\u7b26\u4e32\uff08\"\" \u6216 ''\uff09<\/p>\n<\/li>\n
  • \n
    null<\/p>\n<\/li>\n
  • \n
    undefined<\/p>\n<\/li>\n
  • \n
    NaN<\/p>\n<\/li>\n<\/ul>\n
    \u6240\u4ee5\uff0c\u5982\u679c\u672c\u8eab\u7684\u503c\u53ef\u80fd\u5c31\u662f\u8fd9\u4e9b\u4e2d\u7684\u4e00\u4e2a\uff0c\u5c31\u4e0d\u9002\u5408\u4f7f\u7528\u77ed\u8def\u6c42\u503c\u3002<\/p>\n
    \u77ed\u8def\u6c42\u503c\u8fd8\u80fd\u5728\u51fd\u6570\u8c03\u7528\u4e2d\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u51fd\u6570\u6267\u884c\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    function<\/span> fetchData<\/span>(<\/span>)<\/span> {<\/span><\/span>  if<\/span> (<\/span>shouldFetchData)<\/span> {<\/span><\/span>    return<\/span> fetchDataFromAPI<\/span>(<\/span>)<\/span>;<\/span><\/span>  }<\/span> else<\/span> {<\/span><\/span>    return<\/span> null<\/span>;<\/span><\/span>  }<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    function<\/span> fetchData<\/span>(<\/span>)<\/span> {<\/span><\/span>  return<\/span> shouldFetchData &&<\/span> fetchDataFromAPI<\/span>(<\/span>)<\/span>;<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
    \u5f53 shouldFetchData<\/code> \u4e3a\u771f\u503c\u65f6\uff0c\u77ed\u8def\u6c42\u503c\u4f1a\u7ee7\u7eed\u6267\u884c fetchDataFromAPI()<\/code> \u51fd\u6570\u5e76\u8fd4\u56de\u5176\u7ed3\u679c\u3002\u5982\u679c shouldFetchData<\/code> \u4e3a\u5047\u503c\uff0c\u77ed\u8def\u6c42\u503c\u4f1a\u76f4\u63a5\u8fd4\u56de\u5047\u503c\uff08null<\/code>\uff09\uff0c\u907f\u514d\u4e86\u4e0d\u5fc5\u8981\u7684\u51fd\u6570\u8c03\u7528\u3002<\/p>\n
    \u79d1\u5b66\u8ba1\u6570\u6cd5<\/h2>\n
    \u53ef\u4ee5\u4f7f\u7528\u79d1\u5b66\u6280\u672f\u6cd5\u6765\u8868\u793a\u6570\u5b57\uff0c\u4ee5\u7701\u7565\u5c3e\u90e8\u7684\u96f6\u3002\u4f8b\u5982\uff0c1e7<\/code> \u5b9e\u9645\u4e0a\u8868\u793a 1 \u540e\u9762\u8ddf\u7740 7 \u4e2a\u96f6\u3002\u5b83\u8868\u793a\u4e00\u4e2a\u5341\u8fdb\u5236\uff0c\u76f8\u5f53\u4e8e 10,000,000\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    for<\/span> (<\/span>let<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 10000<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>}<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    for<\/span> (<\/span>let<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> 1e7<\/span>;<\/span> i++<\/span>)<\/span> {<\/span>}<\/span><\/span><\/span>\/\/ \u4e0b\u9762\u7684\u6240\u6709\u6bd4\u8f83\u90fd\u5c06\u8fd4\u56de true<\/span><\/span>1e0<\/span> ===<\/span> 1<\/span>;<\/span><\/span>1e1<\/span> ===<\/span> 10<\/span>;<\/span><\/span>1e2<\/span> ===<\/span> 100<\/span>;<\/span><\/span>1e3<\/span> ===<\/span> 1000<\/span>;<\/span><\/span>1e4<\/span> ===<\/span> 10000<\/span>;<\/span><\/span>1e5<\/span> ===<\/span> 100000<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u4f4d\u8fd0\u7b97\u7b26<\/h2>\n
    \u53cc\u4f4d\u975e\u8fd0\u7b97\u7b26\u6709\u4e00\u4e2a\u975e\u5e38\u5b9e\u7528\u7684\u7528\u9014\uff0c\u53ef\u4ee5\u7528\u5b83\u6765\u66ff\u4ee3Math.floor()<\/code>\u51fd\u6570\uff0c\u5b83\u5728\u6267\u884c\u76f8\u540c\u7684\u64cd\u4f5c\u65f6\u901f\u5ea6\u66f4\u5feb\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    Math.<\/span>floor<\/span>(<\/span>4.9<\/span>)<\/span> ===<\/span> 4<\/span>  \/\/true<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    ~<\/span>~<\/span>4.9<\/span> ===<\/span> 4<\/span>  \/\/true<\/span><\/span><\/code><\/pre>\n
    \u6307\u6570\u5e42\u8fd0\u7b97<\/h2>\n
    \u6307\u6570\u5e42\u8fd0\u7b97\u53ef\u4ee5\u4f7f\u7528 **<\/code> \u6765\u7b80\u5316\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    Math.<\/span>pow<\/span>(<\/span>2<\/span>,<\/span>3<\/span>)<\/span>;<\/span> \/\/ 8<\/span><\/span>Math.<\/span>pow<\/span>(<\/span>2<\/span>,<\/span>2<\/span>)<\/span>;<\/span> \/\/ 4<\/span><\/span>Math.<\/span>pow<\/span>(<\/span>4<\/span>,<\/span>3<\/span>)<\/span>;<\/span> \/\/ 64<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    2<\/span>**<\/span>3<\/span> \/\/ 8<\/span><\/span>2<\/span>**<\/span>4<\/span> \/\/ 4<\/span><\/span>4<\/span>**<\/span>3<\/span> \/\/ 64<\/span><\/span><\/code><\/pre>\n
    \u4ece ES7\uff08ECMAScript 2016\uff09\u5f00\u59cb\uff0cJavaScript \u5f15\u5165\u4e86\u6307\u6570\u5e42\u8fd0\u7b97\u7b26 **<\/code>\uff0c\u4f7f\u6307\u6570\u5e42\u8fd0\u7b97\u66f4\u52a0\u7b80\u6d01\u3002<\/p>\n
    \u53cc\u975e\u672a\u8fd0\u7b97\u7b26<\/h2>\n
    \u5728 JavaScript \u4e2d\uff0c\u53cc\u975e\u4f4d\u8fd0\u7b97\u7b26 ~~<\/code> \u53ef\u4ee5\u7528\u4e8e\u5c06\u6570\u5b57\u5411\u4e0b\u53d6\u6574\uff0c\u7c7b\u4f3c\u4e8e Math.floor()<\/code> \u65b9\u6cd5\u7684\u529f\u80fd\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    const<\/span> floor =<\/span> Math.<\/span>floor<\/span>(<\/span>6.8<\/span>)<\/span>;<\/span> \/\/ 6<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    const<\/span> floor =<\/span> ~<\/span>~<\/span>6.8<\/span>;<\/span> \/\/ 6<\/span><\/span><\/code><\/pre>\n
    \u6ce8\u610f\uff1a\u53cc\u975e\u4f4d\u8fd0\u7b97\u7b26\u53ea\u9002\u7528\u4e8e 32 \u4f4d\u6574\u6570\uff0c\u5373\u8303\u56f4\u4e3a -(2^31) \u5230 (2^31)-1\uff0c\u5373 -2147483648 \u5230 2147483647\u3002\u5bf9\u4e8e\u5927\u4e8e 2147483647 \u6216\u5c0f\u4e8e 0 \u7684\u6570\u5b57\uff0c\u53cc\u975e\u4f4d\u8fd0\u7b97\u7b26\uff08~~<\/code>\uff09\u4f1a\u7ed9\u51fa\u9519\u8bef\u7684\u7ed3\u679c\uff0c\u56e0\u6b64\u5efa\u8bae\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\u4f7f\u7528 Math.floor()<\/code> \u65b9\u6cd5\u3002<\/p>\n
    \u5bf9\u8c61\u5c5e\u6027<\/h2>\n
    ES6 \u63d0\u4f9b\u4e86\u4e00\u79cd\u66f4\u7b80\u6d01\u7684\u65b9\u5f0f\u6765\u7ed9\u5bf9\u8c61\u8d4b\u503c\u5c5e\u6027\u3002\u5982\u679c\u53d8\u91cf\u540d\u4e0e\u5bf9\u8c61\u7684\u952e\u540d\u76f8\u540c\uff0c\u53ef\u4ee5\u5229\u7528\u7b80\u5199\u7b26\u53f7\u6765\u8fdb\u884c\u8d4b\u503c\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    const<\/span> name =<\/span> '\u5fae\u4fe1\u516c\u4f17\u53f7\uff1a\u524d\u7aef\u5145\u7535\u5b9d'<\/span>;<\/span><\/span>const<\/span> age =<\/span> 18<\/span>;<\/span><\/span><\/span>const<\/span> person =<\/span> {<\/span><\/span>  name<\/span>:<\/span> name,<\/span><\/span>  age<\/span>:<\/span> age<\/span>}<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    const<\/span> name =<\/span> '\u5fae\u4fe1\u516c\u4f17\u53f7\uff1a\u524d\u7aef\u5145\u7535\u5b9d'<\/span>;<\/span><\/span>const<\/span> age =<\/span> 30<\/span>;<\/span><\/span><\/span>const<\/span> person =<\/span> {<\/span><\/span>  name,<\/span><\/span>  age<\/span>}<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u7bad\u5934\u51fd\u6570<\/h2>\n
    \u7bad\u5934\u51fd\u6570\u53ef\u4ee5\u7b80\u5316\u7ecf\u5178\u51fd\u6570\u7684\u5199\u6cd5\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    function<\/span> sayHello<\/span>(<\/span>name)<\/span> {<\/span><\/span>  console.<\/span>log<\/span>(<\/span>'Hello'<\/span>,<\/span> name)<\/span>;<\/span><\/span>}<\/span><\/span><\/span>setTimeout<\/span>(<\/span>function<\/span>(<\/span>)<\/span> {<\/span><\/span>  console.<\/span>log<\/span>(<\/span>'Loaded'<\/span>)<\/span><\/span>}<\/span>,<\/span> 2000<\/span>)<\/span>;<\/span><\/span><\/span>list.<\/span>forEach<\/span>(<\/span>function<\/span>(<\/span>item)<\/span> {<\/span><\/span>  console.<\/span>log<\/span>(<\/span>item)<\/span>;<\/span><\/span>}<\/span>)<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    sayHello<\/span> =<\/span> name =><\/span> console.<\/span>log<\/span>(<\/span>'Hello'<\/span>,<\/span> name)<\/span>;<\/span><\/span><\/span>setTimeout<\/span>(<\/span>(<\/span>)<\/span> =><\/span> console.<\/span>log<\/span>(<\/span>'Loaded'<\/span>)<\/span>,<\/span> 2000<\/span>)<\/span>;<\/span><\/span><\/span>list.<\/span>forEach<\/span>(<\/span>item =><\/span> console.<\/span>log<\/span>(<\/span>item)<\/span>)<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u5982\u679c\u7bad\u5934\u51fd\u6570\u53ea\u6709\u4e00\u6761\u8bed\u53e5\uff0c\u5b83\u4f1a\u9690\u5f0f\u5730\u8fd4\u56de\u5176\u6c42\u503c\u7684\u7ed3\u679c\uff0c\u8fd9\u65f6\u53ef\u4ee5\u7701\u7565 return<\/code> \u5173\u952e\u5b57\uff1a<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    function<\/span> calcCircumference<\/span>(<\/span>diameter)<\/span> {<\/span><\/span>  return<\/span> Math.<\/span>PI<\/span> *<\/span> diameter<\/span>}<\/span><\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    calcCircumference<\/span> =<\/span> diameter =><\/span> (<\/span><\/span>  Math.<\/span>PI<\/span> *<\/span> diameter;<\/span><\/span>)<\/span><\/span><\/code><\/pre>\n
    \u53c2\u6570\u89e3\u6784<\/h2>\n
    \u5982\u679c\u6b63\u5728\u4f7f\u7528\u4e00\u4e9b\u6d41\u884c\u7684 Web \u6846\u67b6\uff0c\u6bd4\u5982 React\u3001Vue\uff0c\u53ef\u80fd\u4f1a\u4f7f\u7528\u6570\u7ec4\u6216\u5bf9\u8c61\u5b57\u9762\u91cf\u5f62\u5f0f\u7684\u6570\u636e\u6765\u5728\u7ec4\u4ef6\u4e4b\u95f4\u4f20\u9012\u4fe1\u606f\u3002\u5728\u7ec4\u4ef6\u4e2d\u8981\u60f3\u4f7f\u7528\u6570\u636e\u5bf9\u8c61\uff0c\u5c31\u9700\u8981\u5bf9\u5176\u8fdb\u884c\u89e3\u6784\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    const<\/span> observable =<\/span> require<\/span>(<\/span>'mobx\/observable'<\/span>)<\/span>;<\/span><\/span>const<\/span> action =<\/span> require<\/span>(<\/span>'mobx\/action'<\/span>)<\/span>;<\/span><\/span>const<\/span> runInAction =<\/span> require<\/span>(<\/span>'mobx\/runInAction'<\/span>)<\/span>;<\/span><\/span><\/span>const<\/span> store =<\/span> this<\/span>.<\/span>props.<\/span>store;<\/span><\/span>const<\/span> form =<\/span> this<\/span>.<\/span>props.<\/span>form;<\/span><\/span>const<\/span> loading =<\/span> this<\/span>.<\/span>props.<\/span>loading;<\/span><\/span>const<\/span> errors =<\/span> this<\/span>.<\/span>props.<\/span>errors;<\/span><\/span>const<\/span> entity =<\/span> this<\/span>.<\/span>props.<\/span>entity;<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    import<\/span> {<\/span> observable,<\/span> action,<\/span> runInAction }<\/span> from<\/span> 'mobx'<\/span>;<\/span><\/span><\/span>const<\/span> {<\/span> store,<\/span> form,<\/span> loading,<\/span> errors,<\/span> entity }<\/span> =<\/span> this<\/span>.<\/span>props;<\/span><\/span><\/code><\/pre>\n
    \u8fd8\u53ef\u4ee5\u4e3a\u53d8\u91cf\u8d4b\u4e88\u65b0\u7684\u53d8\u91cf\u540d\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    const<\/span> {<\/span> store,<\/span> form,<\/span> loading,<\/span> errors,<\/span> entity<\/span>:<\/span>contact }<\/span> =<\/span> this<\/span>.<\/span>props;<\/span><\/span><\/code><\/pre>\n
    \u6269\u5c55\u8fd0\u7b97\u7b26<\/h2>\n
    \u5728ES6\u4e2d\u5f15\u5165\u7684\u6269\u5c55\u8fd0\u7b97\u7b26\u53ef\u4ee5\u7b80\u5316\u6570\u7ec4\u548c\u5bf9\u8c61\u7684\u4e00\u4e9b\u64cd\u4f5c\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    \/\/ \u5408\u5e76\u6570\u7ec4<\/span><\/span>const<\/span> odd =<\/span> [<\/span>1<\/span>,<\/span> 3<\/span>,<\/span> 5<\/span>]<\/span>;<\/span><\/span>const<\/span> nums =<\/span> [<\/span>2<\/span>,<\/span> 4<\/span>,<\/span> 6<\/span>]<\/span>.<\/span>concat<\/span>(<\/span>odd)<\/span>;<\/span><\/span>\/\/ \u514b\u9686\u6570\u7ec4<\/span><\/span>const<\/span> arr =<\/span> [<\/span>1<\/span>,<\/span> 2<\/span>,<\/span> 3<\/span>,<\/span> 4<\/span>]<\/span>;<\/span><\/span>const<\/span> arr2 =<\/span> arr.<\/span>slice<\/span>(<\/span>)<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    \/\/ \u5408\u5e76\u6570\u7ec4<\/span><\/span>const<\/span> odd =<\/span> [<\/span>1<\/span>,<\/span> 3<\/span>,<\/span> 5<\/span>]<\/span>;<\/span><\/span>const<\/span> nums =<\/span> [<\/span>2<\/span>,<\/span> 4<\/span>,<\/span> 6<\/span>,<\/span> ...<\/span>odd]<\/span>;<\/span><\/span>console.<\/span>log<\/span>(<\/span>nums)<\/span>;<\/span> \/\/ [ 2, 4, 6, 1, 3, 5 ]<\/span><\/span>\/\/ \u514b\u9686\u6570\u7ec4<\/span><\/span>const<\/span> arr =<\/span> [<\/span>1<\/span>,<\/span> 2<\/span>,<\/span> 3<\/span>,<\/span> 4<\/span>]<\/span>;<\/span><\/span>const<\/span> arr2 =<\/span> [<\/span>...<\/span>arr]<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u4e0e concat()<\/code> \u51fd\u6570\u4e0d\u540c\uff0c\u53ef\u4ee5\u4f7f\u7528\u6269\u5c55\u8fd0\u7b97\u7b26\u5728\u53e6\u4e00\u4e2a\u6570\u7ec4\u7684\u4efb\u610f\u4f4d\u7f6e\u63d2\u5165\u4e00\u4e2a\u6570\u7ec4\u3002<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    const<\/span> odd =<\/span> [<\/span>1<\/span>,<\/span> 3<\/span>,<\/span> 5<\/span>]<\/span>;<\/span><\/span>const<\/span> nums =<\/span> [<\/span>2<\/span>,<\/span> ...<\/span>odd,<\/span> 4<\/span>,<\/span> 6<\/span>]<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u8fd8\u53ef\u4ee5\u5c06\u6269\u5c55\u8fd0\u7b97\u7b26\u4e0eES6\u7684\u89e3\u6784\u8bed\u6cd5\u7ed3\u5408\u4f7f\u7528\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    const<\/span> {<\/span> a,<\/span> b,<\/span> ...<\/span>z }<\/span> =<\/span> {<\/span> a<\/span>:<\/span> 1<\/span>,<\/span> b<\/span>:<\/span> 2<\/span>,<\/span> c<\/span>:<\/span> 3<\/span>,<\/span> d<\/span>:<\/span> 4<\/span> }<\/span>;<\/span><\/span>console.<\/span>log<\/span>(<\/span>a)<\/span> \/\/ 1<\/span><\/span>console.<\/span>log<\/span>(<\/span>b)<\/span> \/\/ 2<\/span><\/span>console.<\/span>log<\/span>(<\/span>z)<\/span> \/\/ { c: 3, d: 4 }<\/span><\/span><\/code><\/pre>\n
    \u6269\u5c55\u8fd0\u7b97\u7b26\u8fd8\u80fd\u7528\u4e8e\u5408\u5e76\u5bf9\u8c61\uff1a<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    let<\/span> fname =<\/span> {<\/span> firstName<\/span> :<\/span> '\u524d\u7aef'<\/span> }<\/span>;<\/span><\/span>let<\/span> lname =<\/span> {<\/span> lastName<\/span> :<\/span> '\u5145\u7535\u5b9d'<\/span>}<\/span><\/span>let<\/span> full_names =<\/span> Object.<\/span>assign<\/span>(<\/span>fname,<\/span> lname)<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    let<\/span> full_names =<\/span> {<\/span>...<\/span>fname,<\/span> ...<\/span>lname}<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u5f3a\u5236\u53c2\u6570<\/h2>\n
    \u5728\u4f20\u7edf\u7684 JavaScript \u5199\u6cd5\u4e2d\uff0c\u4e3a\u4e86\u786e\u4fdd\u51fd\u6570\u53c2\u6570\u88ab\u4f20\u5165\u4e00\u4e2a\u6709\u6548\u503c\uff0c\u6211\u4eec\u9700\u8981\u4f7f\u7528\u6761\u4ef6\u8bed\u53e5\u6765\u629b\u51fa\u4e00\u4e2a\u9519\u8bef\u3002\u53ef\u4ee5\u901a\u8fc7\u4f7f\u7528\u5f3a\u5236\u53c2\u6570\u7b80\u5199\u7684\u5199\u6cd5\u5b9e\u73b0\u76f8\u540c\u7684\u903b\u8f91\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    function<\/span> foo<\/span>(<\/span>bar)<\/span> {<\/span><\/span>  if<\/span>(<\/span>bar ===<\/span> undefined<\/span>)<\/span> {<\/span><\/span>    throw<\/span> new<\/span> Error(<\/span>'Missing parameter!'<\/span>)<\/span>;<\/span><\/span>  }<\/span><\/span>  return<\/span> bar;<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    mandatory<\/span> =<\/span> (<\/span>)<\/span> =><\/span> {<\/span><\/span>  throw<\/span> new<\/span> Error(<\/span>'Missing parameter!'<\/span>)<\/span>;<\/span><\/span>}<\/span><\/span><\/span>foo<\/span> =<\/span> (<\/span>bar =<\/span> mandatory<\/span>(<\/span>)<\/span>)<\/span> =><\/span> {<\/span><\/span>  return<\/span> bar;<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
    \u8fd9\u91cc\u5b9a\u4e49\u4e86\u4e00\u4e2a\u540d\u4e3a mandatory<\/code> \u7684\u51fd\u6570\uff0c\u7528\u4e8e\u629b\u51fa\u4e00\u4e2a\u9519\u8bef\uff0c\u8868\u793a\u51fd\u6570\u53c2\u6570\u672a\u88ab\u4f20\u5165\u3002\u7136\u540e\uff0c\u5728\u51fd\u6570 foo<\/code> \u7684\u53c2\u6570\u5217\u8868\u4e2d\uff0c\u4f7f\u7528\u8d4b\u9ed8\u8ba4\u503c\u7684\u65b9\u5f0f\u6765\u5c06 bar<\/code> \u53c2\u6570\u8bbe\u7f6e\u4e3a mandatory()<\/code> \u7684\u8c03\u7528\u7ed3\u679c\uff0c\u5982\u679c bar<\/code> \u53c2\u6570\u672a\u88ab\u4f20\u5165\u6216\u8005\u4f20\u5165\u4e86\u5047\u503c\uff0c\u5c31\u4f1a\u89e6\u53d1 mandatory()<\/code> \u51fd\u6570\u7684\u6267\u884c\u3002<\/p>\n
    \u8f6c\u4e3a\u5e03\u5c14\u503c<\/h2>\n
    \u53ef\u4ee5\u4f7f\u7528\u53cc\u91cd\u903b\u8f91\u975e\u64cd\u4f5c\u7b26\u5c06\u4efb\u4f55\u503c\u8f6c\u6362\u4e3a\u5e03\u5c14\u503c\u3002<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    !<\/span>!<\/span>23<\/span> \/\/ TRUE<\/span><\/span>!<\/span>!<\/span>\"\"<\/span> \/\/ FALSE<\/span><\/span>!<\/span>!<\/span>0<\/span> \/\/ FALSE<\/span><\/span>!<\/span>!<\/span>{<\/span>}<\/span> \/\/ TRUE<\/span><\/span><\/code><\/pre>\n
    \u5355\u4e00\u7684\u903b\u8f91\u975e\u64cd\u4f5c\u7b26\u5df2\u7ecf\u53ef\u4ee5\u5c06\u503c\u8f6c\u6362\u4e3a\u5e03\u5c14\u7c7b\u578b\u5e76\u5bf9\u5176\u8fdb\u884c\u53d6\u53cd\uff0c\u6240\u4ee5\u7b2c\u4e8c\u4e2a\u903b\u8f91\u975e\u64cd\u4f5c\u7b26\u4f1a\u518d\u6b21\u5bf9\u5176\u8fdb\u884c\u53d6\u53cd\uff0c\u4ece\u800c\u5c06\u5176\u6062\u590d\u4e3a\u539f\u59cb\u542b\u4e49\uff0c\u5e76\u4fdd\u6301\u4e3a\u5e03\u5c14\u7c7b\u578b\u3002<\/p>\n
    \u53d8\u91cf\u4ea4\u6362<\/h2>\n
    \u53ef\u4ee5\u4f7f\u7528\u6570\u7ec4\u89e3\u6784\u6765\u8f7b\u677e\u5b9e\u73b0\u53d8\u91cf\u4ea4\u6362\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff08\u4f7f\u7528\u4e34\u65f6\u53d8\u91cf\u5b8c\u6210\u4e24\u4e2a\u53d8\u91cf\u7684\u4ea4\u6362\uff09\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    let<\/span> a =<\/span> 5<\/span>;<\/span><\/span>let<\/span> b =<\/span> 10<\/span>;<\/span><\/span><\/span>const<\/span> temp =<\/span> a;<\/span><\/span>a =<\/span> b;<\/span><\/span>b =<\/span> temp;<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff08\u4f7f\u7528\u6570\u7ec4\u89e3\u6784\u8d4b\u503c\u5b8c\u6210\u4e24\u4e2a\u53d8\u91cf\u4ea4\u6362\uff09\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    let<\/span> a =<\/span> 5<\/span>;<\/span><\/span>let<\/span> b =<\/span> 10<\/span>;<\/span><\/span><\/span>[<\/span>a,<\/span> b]<\/span> =<\/span> [<\/span>b,<\/span> a]<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u8fd9\u91cc\u521b\u5efa\u4e86\u4e00\u4e2a\u5305\u542b\u4e24\u4e2a\u5143\u7d20\u7684\u6570\u7ec4 [b, a]<\/code>\uff0c\u7136\u540e\u4f7f\u7528\u6570\u7ec4\u89e3\u6784\u8d4b\u503c\u5c06\u5176\u4e2d\u7684\u503c\u5206\u522b\u8d4b\u7ed9\u53d8\u91cf a<\/code> \u548c b<\/code>\u3002\u7531\u4e8e\u5de6\u4fa7\u7684\u6570\u7ec4\u548c\u53f3\u4fa7\u7684\u6570\u7ec4\u7ed3\u6784\u76f8\u540c\uff0c\u6240\u4ee5\u4e24\u4e2a\u503c\u4f1a\u8fdb\u884c\u4ea4\u6362\u3002<\/p>\n
    \u53d8\u91cf\u58f0\u660e<\/h2>\n
    \u5f53\u9700\u8981\u540c\u65f6\u58f0\u660e\u591a\u4e2a\u53d8\u91cf\u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528\u53d8\u91cf\u58f0\u660e\u7684\u7b80\u5199\u65b9\u6cd5\u6765\u8282\u7701\u65f6\u95f4\u548c\u7a7a\u95f4\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    let<\/span> x;<\/span><\/span>let<\/span> y;<\/span><\/span>let<\/span> z =<\/span> 3<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    let<\/span> x,<\/span> y,<\/span> z =<\/span> 3<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u4e0d\u8fc7\uff0c\u8fd9\u4e2a\u4f18\u5316\u6709\u4e9b\u4e89\u8bae\uff0c\u5f88\u591a\u4eba\u8ba4\u4e3a\u8fd9\u4e48\u5199\u4f1a\u5f71\u54cd\u4ee3\u7801\u7684\u53ef\u8bfb\u6027\uff0c\u56e0\u4e3a\u8bb8\u591a\u53d8\u91cf\u5199\u5230\u4e86\u4e00\u884c\uff0c\u4e0d\u5982\u4e00\u4e2a\u53d8\u91cf\u4e00\u884c\u66f4\u6e05\u6670\u660e\u4e86\uff0c\u6240\u4ee5\u53ef\u4ee5\u9009\u62e9\u6027\u91c7\u7528\u3002<\/p>\n
    \u5982\u679c\u6709\u591a\u4e2a\u53d8\u91cf\u9700\u8981\u8d4b\u76f8\u540c\u7684\u503c\uff0c\u5219\u53ef\u4ee5\u4f7f\u7528\u8fde\u7b49\u6765\u5b9e\u73b0\u3002<\/p>\n
    \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    let<\/span> a =<\/span> 100<\/span>;<\/span><\/span>let<\/span> b =<\/span> 100<\/span>;<\/span><\/span>let<\/span> c =<\/span> 100<\/span>;<\/span><\/span><\/code><\/pre>\n
    \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
    <\/span><\/span><\/span><\/span> <\/span><\/section>
    let<\/span> a =<\/span> b =<\/span> c =<\/span> 100<\/span>;<\/span><\/span><\/code><\/pre>\n
    For \u5faa\u73af<\/h2>\n
    JavaScript \u4e2d\u4f20\u7edf\u7684 for \u5faa\u73af\u8bed\u6cd5\u4f7f\u7528\u6570\u7ec4\u7684\u957f\u5ea6\u4f5c\u4e3a\u8fed\u4ee3\u5668\u6765\u904d\u5386\u6570\u7ec4\u3002\u8fd8\u6709\u5f88\u591a for \u5faa\u73af\u7684\u5feb\u6377\u65b9\u5f0f\u63d0\u4f9b\u4e86\u5728\u6570\u7ec4\u4e2d\u8fed\u4ee3\u5bf9\u8c61\u7684\u4e0d\u540c\u65b9\u6cd5\uff0c\u4f8b\u5982\uff1a<\/p>\n
      \n
    • \n
      for...of<\/code>\uff1a\u7528\u4e8e\u904d\u5386\u5185\u7f6e\u5b57\u7b26\u4e32\u3001\u6570\u7ec4\u3001\u7c7b\u6570\u7ec4\u5bf9\u8c61\u3001NodeList\u3002<\/p>\n<\/li>\n
    • \n
      for...in<\/code>\uff1a\u7528\u4e8e\u8bbf\u95ee\u6570\u7ec4\u7684\u7d22\u5f15\u548c\u5bf9\u5bf9\u8c61\u5b57\u9762\u91cf\u8fdb\u884c\u904d\u5386\uff0c\u5e76\u8bb0\u5f55\u5c5e\u6027\u540d\u79f0\u548c\u503c\u7684\u5b57\u7b26\u4e32\u3002<\/p>\n<\/li>\n
    • \n
      Array.forEach<\/code>\uff1a\u4f7f\u7528\u56de\u8c03\u51fd\u6570\u5bf9\u6570\u7ec4\u5143\u7d20\u53ca\u5176\u7d22\u5f15\u6267\u884c\u64cd\u4f5c\u3002<\/p>\n<\/li>\n<\/ul>\n
      \u4f20\u7edf\u5199\u6cd5\uff1a<\/p>\n
      <\/span><\/span><\/span><\/span> <\/span><\/section>
      <\/span>for<\/span> (<\/span>let<\/span> i =<\/span> 0<\/span>;<\/span> i <<\/span> arr.<\/span>length;<\/span> i++<\/span>)<\/span> {<\/span><\/span>  console.<\/span>log<\/span>(<\/span>\"item: \"<\/span>,<\/span> arr[<\/span>i]<\/span>)<\/span>;<\/span>}<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
      \u7b80\u5316\u5199\u6cd5\uff1a<\/p>\n
      <\/span><\/span><\/span><\/span> <\/span><\/section>
      for<\/span> (<\/span>let<\/span> str of<\/span> arr)<\/span> {<\/span><\/span>  console.<\/span>log<\/span>(<\/span>\"item: \"<\/span>,<\/span> str)<\/span>;<\/span><\/span>}<\/span><\/span><\/span>arr.<\/span>forEach<\/span>(<\/span>(<\/span>str)<\/span> =><\/span> {<\/span><\/span>  console.<\/span>log<\/span>(<\/span>\"item: \"<\/span>,<\/span> str)<\/span>;<\/span><\/span>}<\/span>)<\/span>;<\/span><\/span><\/span>for<\/span> (<\/span>let<\/span> index in<\/span> arr)<\/span> {<\/span><\/span>  console.<\/span>log<\/span>(<\/span>index,<\/span> arr[<\/span>index]<\/span>)<\/span>;<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
      \u5bf9\u4e8e\u5bf9\u8c61\u5b57\u9762\u91cf\uff0c\u4e5f\u53ef\u4ee5\u4f7f\u7528 for...in<\/code> \u6765\u904d\u5386:<\/p>\n
      <\/span><\/span><\/span><\/span> <\/span><\/section>
      const<\/span> obj =<\/span> {<\/span> a<\/span>:<\/span> 1<\/span>,<\/span> b<\/span>:<\/span> 3<\/span>,<\/span> c<\/span>:<\/span> 5<\/span> }<\/span>;<\/span><\/span><\/span>for<\/span> (<\/span>let<\/span> key in<\/span> obj)<\/span> {<\/span><\/span>  console.<\/span>log<\/span>(<\/span>key,<\/span> obj[<\/span>key]<\/span>)<\/span>;<\/span><\/span>}<\/span><\/span><\/code><\/pre>\n
      <\/mp-common-profile><\/section>\n<\/section>\n<\/section>\n
      <\/mp-style-type><\/p>\n
      \n
      \u672c\u7bc7\u6587\u7ae0\u6765\u6e90\u4e8e\u5fae\u4fe1\u516c\u4f17\u53f7:                 \u6280\u672f\u80d6\u5b66\u7a0b\u5e8f              <\/p>\n<\/blockquote>\n<\/div>\n","raw":"","protected":false},"excerpt":{"rendered":"
      JavaScript \u4e2d\u6709\u5f88\u591a\u7b80\u5199\u6280\u5de7\uff0c\u53ef\u4ee5\u7f29\u77ed\u4ee3\u7801\u957f\u5ea6\u3001\u51cf\u5c11\u5197\u4f59\uff0c\u5e76\u4e14\u63d0\u9ad8\u4ee3\u7801\u7684\u53ef\u8bfb\u6027\u548c\u53ef\u7ef4\u62a4\u6027\u3002\u672c\u6587\u5c06\u4ecb\u7ecd 20 \u4e2a\u63d0\u5347\u6548\u7387\u7684 …<\/p>\n","protected":false},"author":1,"featured_media":3208,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"emotion":"","emotion_color":"","title_style":"","license":"","footnotes":""},"categories":[13],"tags":[],"class_list":["post-3210","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-vue"],"post_thumbnail_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/11\/20231102165256796-150x150.jpeg","content_first_image":null,"post_medium_image_300":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/11\/20231102165256796-300x127.jpeg","post_thumbnail_image_624":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/11\/20231102165256796.jpeg","post_frist_image":null,"post_medium_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/11\/20231102165256796-300x127.jpeg","post_large_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/11\/20231102165256796.jpeg","post_full_image":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/11\/20231102165256796.jpeg","post_all_images":[],"videoAdId":"","listAd":"0","listAdId":"","listAdEvery":6,"total_comments":0,"category_name":"Vue","post_date":"2023-11-02","like_count":"0","praiseWord":"\u9f13\u52b1","copyright_state":"","excitationAd":"0","rewardedVideoAdId":"","detailAdId":"","detailAd":"0","enterpriseMinapp":"0","audios":[],"postImageUrl":"https:\/\/wp-moto-1258805347.cos.ap-shanghai.myqcloud.com\/2023\/05\/20230519082947553.jpg","avatarurls":[],"related_posts":null,"pageviews":929,"next_post_id":6489,"next_post_title":"\u5982\u4f55\u4e3a\u81ea\u5df1\u7684WordPress\u535a\u5ba2\u6dfb\u52a0\u4e00\u4e2a\u53ef\u7231\u7684\u5609\u7136\u770b\u677f\u5a18\uff01(\u4fdd\u59c6\u7ea7)","previous_post_id":3473,"previous_post_title":"\u524d\u7aef\u7ebf\u4e0a\u90e8\u7f72\uff0c\u5982\u4f55\u901a\u77e5\u7528\u6237\u6709\u65b0\u7248\u672c\uff1f\uff1f\uff1f","_links":{"self":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/3210","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/comments?post=3210"}],"version-history":[{"count":1,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/3210\/revisions"}],"predecessor-version":[{"id":3624,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/posts\/3210\/revisions\/3624"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/media\/3208"}],"wp:attachment":[{"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/media?parent=3210"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/categories?post=3210"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xinchewhd.com.cn\/index.php\/wp-json\/wp\/v2\/tags?post=3210"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}