{"id":164206,"date":"2024-05-08T14:49:44","date_gmt":"2024-05-08T06:49:44","guid":{"rendered":"https:\/\/docs.pingcode.com\/ask\/ask-ask\/164206.html"},"modified":"2024-05-08T14:49:46","modified_gmt":"2024-05-08T06:49:46","slug":"web%e5%89%8d%e7%ab%af%ef%bc%9ajavascript%e4%b8%ad%e7%9a%84nan%e6%98%af%e4%bb%80%e4%b9%88","status":"publish","type":"post","link":"https:\/\/docs.pingcode.com\/ask\/ask-ask\/164206.html","title":{"rendered":"Web\u524d\u7aef\uff1aJavaScript\u4e2d\u7684NaN\u662f\u4ec0\u4e48"},"content":{"rendered":"

\"Web\u524d\u7aef\uff1aJavaScript\u4e2d\u7684NaN\u662f\u4ec0\u4e48\"<\/p>\n

JavaScript\u4e2d\u7684NaN\u4ee3\u8868Not-a-Number<\/strong>\uff0c\u5b83\u662f\u4e00\u79cd\u7279\u6b8a\u7684\u6570\u503c\uff0c\u7528\u4e8e\u6307\u793a\u67d0\u4e2a\u64cd\u4f5c\u7684\u7ed3\u679c\u4e0d\u662f\u6709\u6548\u7684\u6570\u5b57\u3002NaN\u662f\u5168\u5c40\u5bf9\u8c61\u7684\u4e00\u4e2a\u5c5e\u6027\uff0c\u5728\u8fdb\u884c\u6570\u5b66\u8fd0\u7b97\u65f6\uff0c\u5982\u679c\u8fd0\u7b97\u7684\u7ed3\u679c\u65e0\u6cd5\u5f97\u51fa\u4e00\u4e2a\u786e\u5207\u7684\u6570\u5b57\u503c\uff0c\u5219\u4f1a\u8fd4\u56deNaN\u3002\u4f8b\u5982\uff0c\u5f53\u6211\u4eec\u5c1d\u8bd5\u5c06\u5b57\u7b26\u4e32\u89e3\u6790\u4e3a\u6570\u5b57\u800c\u5b57\u7b26\u4e32\u4e0d\u5177\u5907\u6570\u503c\u7279\u6027\u65f6\uff0c\u5c31\u4f1a\u4ea7\u751fNaN\u3002\u53e6\u4e00\u4e2a\u4ea7\u751fNaN\u7684\u5178\u578b\u573a\u666f\u662f\u4e24\u4e2a\u4e0d\u517c\u5bb9\u7684\u7c7b\u578b\u8fdb\u884c\u7b97\u672f\u8fd0\u7b97\u65f6<\/strong>\uff0c\u6bd4\u5982\u4e00\u4e2a\u6570\u5b57\u9664\u4ee5\u4e00\u4e2a\u5b57\u7b26\u4e32\u3002NaN\u6709\u51e0\u4e2a\u72ec\u7279\u7684\u7279\u6027\uff0c\u6700\u4e3b\u8981\u7684\u662f\u5b83\u4e0e\u4efb\u4f55\u503c\u90fd\u4e0d\u76f8\u7b49\uff0c\u5305\u62ec\u5b83\u81ea\u5df1\uff0c\u5373NaN === NaN<\/code>\u7684\u7ed3\u679c\u4e3afalse<\/code>\u3002\u8fd9\u5c31\u610f\u5473\u7740\u6211\u4eec\u4e0d\u80fd\u901a\u8fc7\u5e38\u89c4\u7684\u6bd4\u8f83\u64cd\u4f5c\u6765\u68c0\u6d4b\u4e00\u4e2a\u503c\u662f\u5426\u662fNaN\uff0c\u800c\u5e94\u8be5\u4f7f\u7528isNaN()<\/code>\u51fd\u6570\u3002<\/p>\n<\/p>\n

\u4e00\u3001NaN\u7684\u4ea7\u751f\u4e0e\u68c0\u6d4b<\/h3>\n<\/p>\n

NaN\u7684\u4ea7\u751f<\/strong>\uff1a<\/p>\n<\/p>\n

NaN\u53ef\u80fd\u5728\u6267\u884c\u6570\u5b66\u8fd0\u7b97\u65f6\u51fa\u73b0\uff0c\u5c24\u5176\u662f\u8fd9\u4e9b\u8fd0\u7b97\u6ca1\u6709\u660e\u786e\u610f\u4e49\u6216\u65e0\u6cd5\u8fd4\u56de\u4e00\u4e2a\u5177\u4f53\u6570\u5b57\u7684\u65f6\u5019\u3002\u4ee5\u4e0b\u60c5\u51b5\u4f1a\u5bfc\u81f4NaN\u7684\u4ea7\u751f\uff1a<\/p>\n<\/p>\n

    \n
  • \u975e\u6570\u5b57\u7c7b\u578b\u4e0e\u6570\u5b57\u7c7b\u578b\u8fdb\u884c\u7b97\u672f\u8fd0\u7b97\uff0c\u5982"a" * 2<\/code>\u3002<\/li>\n
  • \u65e0\u6cd5\u89e3\u6790\u6210\u6570\u5b57\u7684\u5b57\u7b26\u4e32\u4f20\u9012\u7ed9Number()<\/code>\u6784\u9020\u51fd\u6570\uff0c\u5982Number("invalid number")<\/code>\u3002<\/li>\n
  • \u6570\u5b66\u8fd0\u7b97\u7684\u7ed3\u679c\u8d85\u51faJavaScript\u80fd\u8868\u793a\u7684\u6570\u5b57\u8303\u56f4\uff0c\u5982Math.sqrt(-1)<\/code>\u3002<\/li>\n
  • \u8fd0\u7b97\u8fc7\u7a0b\u4e2d\u6267\u884c\u4e86\u4e0d\u5408\u6cd5\u7684\u6570\u5b66\u64cd\u4f5c\uff0c\u59820\/0<\/code>\u3002<\/li>\n<\/ul>\n

    NaN\u7684\u68c0\u6d4b<\/strong>\uff1a<\/p>\n<\/p>\n

    \u7531\u4e8eNaN\u7684\u7279\u6b8a\u6027\u8d28\u4f7f\u5f97\u4e0d\u80fd\u7528\u666e\u901a\u7684\u76f8\u7b49\u64cd\u4f5c\u7b26\uff08==<\/code>\u6216===<\/code>\uff09\u6765\u68c0\u6d4b\u3002JavaScript\u63d0\u4f9b\u4e86isNaN()<\/code>\u5168\u5c40\u51fd\u6570\u6765\u68c0\u6d4b\u4e00\u4e2a\u503c\u662f\u5426\u662fNaN\uff1a<\/p>\n<\/p>\n

    if (isNaN(value)) {<\/p>\n
      console.log('Value is NaN');<\/p>\n
    }<\/p>\n
    <\/code><\/pre>\n<\/p>\n
    \u6b64\u5916\uff0cES6\u5f15\u5165\u4e86\u4e00\u4e2a\u66f4\u52a0\u4e25\u683c\u7684Number.isNaN()<\/code>\u65b9\u6cd5\uff0c\u5b83\u53ea\u6709\u5728\u503c\u771f\u6b63\u4e3aNaN\u65f6\u624d\u8fd4\u56detrue<\/code>\uff0c\u800cisNaN()<\/code>\u4f1a\u5148\u5c1d\u8bd5\u5c06\u975e\u6570\u5b57\u7684\u53c2\u6570\u8f6c\u6362\u4e3a\u6570\u5b57\uff0c\u53ea\u6709\u5f53\u8f6c\u6362\u540e\u7684\u7ed3\u679c\u662fNaN\u65f6\u624d\u8fd4\u56detrue<\/code>\u3002\u56e0\u6b64\uff0cNumber.isNaN()<\/code>\u5bf9\u4e8e\u7cbe\u786e\u68c0\u6d4bNaN\u66f4\u52a0\u53ef\u9760\u3002<\/p>\n<\/p>\n
    \u4e8c\u3001NaN\u7684\u6bd4\u8f83\u4e0e\u8f6c\u6362<\/h3>\n<\/p>\n
    NaN\u7684\u6bd4\u8f83<\/strong>\uff1a<\/p>\n<\/p>\n
    \u6b63\u5982\u524d\u6587\u6240\u8ff0\uff0cNaN\u662f\u552f\u4e00\u4e00\u4e2a\u4e0d\u7b49\u4e8e\u5176\u672c\u8eab\u7684\u503c\u3002\u56e0\u6b64\uff0c\u4e24\u4e2aNaN\u4e4b\u95f4\u7684\u6bd4\u8f83\u6c38\u8fdc\u8fd4\u56defalse<\/code>\uff1a<\/p>\n<\/p>\n
    console.log(NaN === NaN); \/\/ \u8f93\u51fa: false<\/p>\n
    <\/code><\/pre>\n<\/p>\n
    \u5373\u4f7f\u662f\u5728\u6570\u7ec4\u4e2d\u4f7f\u7528indexOf<\/code>\u65b9\u6cd5\u6216\u5176\u4ed6\u67e5\u627e\u7b97\u6cd5\uff0c\u4e5f\u65e0\u6cd5\u627e\u5230NaN\u5143\u7d20\uff0c\u56e0\u4e3a\u67e5\u627e\u8fc7\u7a0b\u4e2d\u4f1a\u7528\u5230\u76f8\u7b49\u7684\u6bd4\u8f83\u3002\u8fd9\u4e5f\u610f\u5473\u7740\u5224\u65ad\u4e00\u4e2a\u503c\u662f\u5426\u4e3aNaN\u5fc5\u987b\u4f7f\u7528isNaN()<\/code>\u6216Number.isNaN()<\/code>\u65b9\u6cd5\u3002<\/p>\n<\/p>\n
    NaN\u7684\u8f6c\u6362<\/strong>\uff1a<\/p>\n<\/p>\n
    \u5c3d\u7ba1NaN\u4ee3\u8868\u975e\u6570\u5b57\uff0c\u4f46\u5b83\u5b9e\u9645\u4e0a\u662fNumber<\/code>\u7c7b\u578b\u3002\u4f8b\u5982\uff0c\u6211\u4eec\u53ef\u4ee5\u5c06NaN\u4f7f\u7528+<\/code>\u8fd0\u7b97\u7b26\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\u7c7b\u578b\uff1a<\/p>\n<\/p>\n
    console.log(NaN + ""); \/\/ \u8f93\u51fa: "NaN"<\/p>\n
    <\/code><\/pre>\n<\/p>\n
    \u6b64\u65f6NaN\u4f5c\u4e3a\u4e00\u4e2a\u5b57\u7b26\u4e32\u201cNaN\u201d\u5b58\u5728\u3002\u5728\u5e03\u5c14\u4e0a\u4e0b\u6587\u4e2d\uff0c\u5982if<\/code>\u8bed\u53e5\u91cc\uff0cNaN\u88ab\u5f53\u4f5cfalse<\/code>\u5904\u7406\u3002<\/p>\n<\/p>\n
    \u4e09\u3001NaN\u5728\u5b9e\u9645\u7f16\u7a0b\u4e2d\u7684\u5f71\u54cd<\/h3>\n<\/p>\n
    \u5728\u5b9e\u9645\u7f16\u7a0b\u4e2d\uff0c\u907f\u514d\u5f02\u5e38\u6216\u610f\u5916\u7684NaN\u503c\u662f\u975e\u5e38\u91cd\u8981\u7684\u3002NaN\u53ef\u80fd\u4f1a\u5728\u8868\u8fbe\u5f0f\u4e2d\u4f20\u64ad\uff1a\u4e00\u65e6\u67d0\u4e2a\u64cd\u4f5c\u7b26\u7684\u64cd\u4f5c\u6570\u4e3aNaN\uff0c\u6574\u4e2a\u8fd0\u7b97\u7ed3\u679c\u901a\u5e38\u90fd\u4f1a\u662fNaN\u3002\u8fd9\u53ef\u80fd\u5bfc\u81f4\u590d\u6742\u7684\u9519\u8bef\u548c\u7a0b\u5e8f\u7684\u4e0d\u7a33\u5b9a\uff0c\u5728\u8c03\u8bd5\u65f6\u4e5f\u4e0d\u5bb9\u6613\u5b9a\u4f4d\u95ee\u9898\u6765\u6e90\u3002\u56e0\u6b64\uff0c\u5f00\u53d1\u4eba\u5458\u5728\u7f16\u5199\u4ee3\u7801\u65f6\u5e94\u5f53\u6ce8\u610f\uff1a<\/p>\n<\/p>\n
      \n
    • \u9a8c\u8bc1\u8f93\u5165\u503c\u662f\u5426\u53ef\u4ee5\u8f6c\u6362\u4e3a\u6709\u6548\u7684\u6570\u5b57\u3002<\/li>\n
    • \u786e\u4fdd\u8868\u8fbe\u5f0f\u4e2d\u7684\u8fd0\u7b97\u7b26\u5e94\u7528\u4e8e\u9884\u671f\u7684\u6570\u636e\u7c7b\u578b\u3002<\/li>\n
    • \u5c3d\u91cf\u4f7f\u7528Number.isNaN()<\/code>\u66ff\u4ee3isNaN()<\/code>\uff0c\u4ee5\u907f\u514d\u81ea\u52a8\u7c7b\u578b\u8f6c\u6362\u53ef\u80fd\u5bfc\u81f4\u7684\u8bef\u5224\u3002<\/li>\n<\/ul>\n
      \u56db\u3001JavaScript\u4e2d\u907f\u514d\u548c\u5904\u7406NaN<\/h3>\n<\/p>\n
      \u5982\u4f55\u907f\u514dNaN<\/strong>\uff1a<\/p>\n<\/p>\n
      \u8981\u907f\u514dNaN\uff0c\u5173\u952e\u662f\u786e\u4fdd\u6240\u6709\u7684\u6570\u5b66\u8fd0\u7b97\u90fd\u9488\u5bf9\u6709\u6548\u7684\u6570\u5b57\u548c\u9884\u671f\u7684\u7c7b\u578b\u3002\u5728\u9700\u8981\u5c06\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u6570\u5b57\u65f6\uff0c\u4f7f\u7528\u5982parseInt<\/code>\u548cparseFloat<\/code>\u7b49\u51fd\u6570\uff0c\u5e76\u9a8c\u8bc1\u8f6c\u6362\u7ed3\u679c\u3002\u5728\u6d89\u53ca\u590d\u6742\u8ba1\u7b97\u7684\u51fd\u6570\u4e2d\uff0c\u8003\u8651\u52a0\u5165\u5bf9\u7ed3\u679c\u7684\u5f02\u5e38\u68c0\u67e5\u3002<\/p>\n<\/p>\n
      \u5904\u7406NaN\u7684\u7b56\u7565<\/strong>\uff1a<\/p>\n<\/p>\n
      \u5982\u679c\u4f60\u7684\u51fd\u6570\u53ef\u80fd\u4f1a\u8fd4\u56deNaN\uff0c\u4f60\u5e94\u8be5\u8bbe\u8ba1\u4e00\u79cd\u65b9\u5f0f\u6765\u5904\u7406\u8fd9\u4e2a\u503c\u3002\u53ef\u80fd\u7684\u7b56\u7565\u5305\u62ec\uff1a<\/p>\n<\/p>\n
        \n
      • \u8fd4\u56de\u4e00\u4e2a\u9ed8\u8ba4\u503c\u3002<\/li>\n
      • \u4f7f\u7528null<\/code>\u6216undefined<\/code>\u6765\u8868\u793a\u65e0\u6548\u7684\u6570\u503c\u3002<\/li>\n
      • \u629b\u51fa\u4e00\u4e2a\u9519\u8bef\uff0c\u5f3a\u5236\u8c03\u7528\u8005\u5904\u7406\u8fd9\u79cd\u60c5\u51b5\u3002<\/li>\n<\/ul>\n
        \u603b\u800c\u8a00\u4e4b\uff0c\u4f5c\u4e3a\u4e00\u540d\u5f00\u53d1\u4eba\u5458\uff0c\u7406\u89e3NaN\u5e76\u77e5\u9053\u5982\u4f55\u6070\u5f53\u5730\u7ba1\u7406\u5b83\uff0c\u662f\u786e\u4fdd\u4f60\u7684JavaScript\u7a0b\u5e8f\u7a33\u5b9a\u6027\u548c\u53ef\u9760\u6027\u7684\u5173\u952e\u56e0\u7d20\u3002\u901a\u8fc7\u907f\u514d\u4e0d\u5fc5\u8981\u7684NaN\uff0c\u5e76\u6b63\u786e\u5730\u5904\u7406\u65e0\u6cd5\u907f\u514d\u7684NaN\uff0c\u4f60\u80fd\u591f\u63d0\u5347\u4f60\u7684\u7a0b\u5e8f\u7684\u5065\u58ee\u6027\u548c\u7528\u6237\u4f53\u9a8c\u3002<\/p>\n<\/p>\n
        \u76f8\u5173\u95ee\u7b54FAQs\uff1a<\/strong><\/h2>\n
        1. JavaScript\u4e2d\u7684NaN\u4ee3\u8868\u4ec0\u4e48\uff1f<\/strong><\/p>\n
        NaN\u662fJavaScript\u4e2d\u7684\u7279\u6b8a\u503c\uff0c\u8868\u793a"\u975e\u6570\u5b57"\u3002\u5f53\u8fdb\u884c\u6570\u5b66\u8fd0\u7b97\u65f6\uff0c\u5982\u679c\u7ed3\u679c\u65e0\u6cd5\u8868\u793a\u4e3a\u6709\u6548\u7684\u6570\u5b57\uff0c\u5c31\u4f1a\u8fd4\u56deNaN\u3002\u8fd9\u53ef\u4ee5\u53d1\u751f\u5728\u4ee5\u4e0b\u60c5\u51b5\u4e0b\uff1a\u9664\u4ee50\uff0c\u5c06\u975e\u6570\u5b57\u503c\u4e0e\u6570\u5b57\u76f8\u52a0\uff0c\u6216\u8005\u6267\u884c\u5176\u4ed6\u65e0\u6cd5\u8bc6\u522b\u4e3a\u6570\u5b57\u7684\u64cd\u4f5c\u3002<\/p>\n
        2. NaN\u5728JavaScript\u4e2d\u7684\u5e94\u7528\u573a\u666f\u662f\u4ec0\u4e48\uff1f<\/strong><\/p>\n
        NaN\u901a\u5e38\u7528\u4e8e\u8868\u793a\u65e0\u6548\u7684\u6216\u672a\u5b9a\u4e49\u7684\u6570\u503c\uff0c\u53ef\u4ee5\u7528\u4e8e\u68c0\u67e5\u8fd0\u7b97\u7ed3\u679c\u662f\u5426\u662f\u6709\u6548\u6570\u5b57\u3002\u4f8b\u5982\uff0c\u5f53\u5728\u7528\u6237\u8f93\u5165\u7684\u8868\u5355\u4e2d\u9a8c\u8bc1\u6570\u503c\u65f6\uff0c\u53ef\u4ee5\u4f7f\u7528isNaN()\u51fd\u6570\u6765\u5224\u65ad\u8f93\u5165\u662f\u5426\u4e3a\u6570\u5b57\u3002\u5982\u679cisNaN()\u8fd4\u56detrue\uff0c\u8be5\u8f93\u5165\u5c31\u662f\u65e0\u6548\u7684\u6570\u503c\u3002<\/p>\n
        3. \u5982\u4f55\u5904\u7406JavaScript\u4e2d\u7684NaN\u503c\uff1f<\/strong><\/p>\n
        \u5f53\u6d89\u53ca\u5230NaN\u65f6\uff0c\u6211\u4eec\u9700\u8981\u5c0f\u5fc3\u5904\u7406\uff0c\u4ee5\u786e\u4fdd\u6b63\u786e\u7684\u6570\u5b66\u8fd0\u7b97\u548c\u903b\u8f91\u5224\u65ad\u3002\u4ee5\u4e0b\u662f\u5904\u7406NaN\u7684\u4e00\u4e9b\u5efa\u8bae\uff1a<\/p>\n
          \n
        • \u4f7f\u7528isNaN()\u51fd\u6570\u6765\u68c0\u67e5\u503c\u662f\u5426\u4e3aNaN\uff0c\u4ee5\u4fbf\u8fdb\u884c\u76f8\u5e94\u7684\u5904\u7406\u3002<\/li>\n
        • \u4f7f\u7528isNaN()\u51fd\u6570\u4e4b\u524d\uff0c\u9996\u5148\u786e\u5b9a\u503c\u662f\u6570\u5b57\u7c7b\u578b\uff0c\u53ef\u4ee5\u4f7f\u7528typeof\u8fd0\u7b97\u7b26\u8fdb\u884c\u68c0\u67e5\u3002<\/li>\n
        • \u4f7f\u7528isNaN()\u4e0eNumber.isNaN()\u8fdb\u884c\u6bd4\u8f83\uff0cNumber.isNaN()\u4f1a\u6392\u9664\u975e\u6570\u5b57\u503c\u7684\u60c5\u51b5\u3002<\/li>\n
        • \u5728\u6267\u884c\u6570\u503c\u8ba1\u7b97\u4e4b\u524d\uff0c\u53ef\u4ee5\u4f7f\u7528parseFloat()\u6216parseInt()\u51fd\u6570\u5c06\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u6570\u5b57\uff0c\u5982\u679c\u65e0\u6cd5\u8f6c\u6362\uff0c\u5219\u4f1a\u8fd4\u56deNaN\u3002<\/li>\n
        • \u4f7f\u7528\u6761\u4ef6\u8bed\u53e5\uff08\u5982if\u8bed\u53e5\uff09\u5c06NaN\u4e0e\u5176\u4ed6\u503c\u8fdb\u884c\u6bd4\u8f83\uff0c\u4ee5\u63a7\u5236\u7a0b\u5e8f\u7684\u6d41\u7a0b\u3002<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"JavaScript\u4e2d\u7684NaN\u4ee3\u8868Not-a-Number\uff0c\u5b83\u662f\u4e00\u79cd\u7279\u6b8a\u7684\u6570\u503c\uff0c\u7528\u4e8e\u6307\u793a\u67d0\u4e2a\u64cd\u4f5c\u7684\u7ed3\u679c\u4e0d\u662f\u6709\u6548 […]","protected":false},"author":3,"featured_media":164207,"comment_status":"closed","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[37],"tags":[],"acf":[],"_links":{"self":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/164206"}],"collection":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/comments?post=164206"}],"version-history":[{"count":0,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/164206\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media\/164207"}],"wp:attachment":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media?parent=164206"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/categories?post=164206"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/tags?post=164206"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}