{"id":169697,"date":"2024-05-08T16:51:30","date_gmt":"2024-05-08T08:51:30","guid":{"rendered":"https:\/\/docs.pingcode.com\/ask\/ask-ask\/169697.html"},"modified":"2024-05-08T16:51:34","modified_gmt":"2024-05-08T08:51:34","slug":"javascript-%e5%9f%ba%e6%9c%ac%e7%b1%bb%e5%9e%8b%e7%9a%84%e5%80%bc%e5%88%b0%e5%ba%95%e6%98%af%e4%b8%8d%e6%98%af%e5%8f%af%e5%8f%98%e7%9a%84","status":"publish","type":"post","link":"https:\/\/docs.pingcode.com\/ask\/169697.html","title":{"rendered":"javascript \u57fa\u672c\u7c7b\u578b\u7684\u503c\u5230\u5e95\u662f\u4e0d\u662f\u53ef\u53d8\u7684"},"content":{"rendered":"

\"javascript<\/p>\n

JavaScript\u57fa\u672c\u7c7b\u578b\u7684\u503c\u662f\u4e0d\u53ef\u53d8\u7684<\/strong>\u3002\u8fd9\u4e9b\u57fa\u672c\u7c7b\u578b\u5305\u62ec Undefined\u3001Null\u3001Boolean\u3001Number\u3001String\u3001Symbol\uff08ES6 \u65b0\u589e\uff09\u4ee5\u53ca BigInt\uff08ES2020 \u65b0\u63a8\u51fa\u7684\u5927\u6574\u6570\u7c7b\u578b\uff09\u3002\u4f8b\u5982\uff0c\u5b57\u7b26\u4e32\u662f\u7531\u5b57\u7b26\u7ec4\u6210\u7684\u5e8f\u5217\uff0c\u4e00\u65e6\u521b\u5efa\uff0c\u65e0\u6cd5\u66f4\u6539\u5b57\u7b26\u4e32\u4e2d\u7684\u5b57\u7b26\u3002\u5982\u679c\u4f60\u5bf9\u5b57\u7b26\u4e32\u8fdb\u884c\u4e86\u4fee\u6539\uff0c\u5982\u62fc\u63a5\u3001\u66ff\u6362\u7b49\u64cd\u4f5c\uff0c\u5b9e\u9645\u4e0a\u662f\u521b\u5efa\u4e86\u4e00\u4e2a\u65b0\u7684\u5b57\u7b26\u4e32\uff0c\u539f\u59cb\u7684\u5b57\u7b26\u4e32\u5e76\u672a\u53d1\u751f\u53d8\u5316\u3002<\/p>\n<\/p>\n

\u4e00\u3001\u57fa\u672c\u7c7b\u578b\u4e0e\u53ef\u53d8\u6027<\/h3>\n<\/p>\n

\u57fa\u672c\u7c7b\u578b\uff08\u539f\u59cb\u7c7b\u578b\uff09\u7684\u4e0d\u53ef\u53d8\u6027\u610f\u5473\u7740\u5b83\u4eec\u7684\u503c\u4e00\u65e6\u88ab\u521b\u5efa\uff0c\u5c31\u65e0\u6cd5\u6539\u53d8\u3002\u8fd9\u4e0e\u5f15\u7528\u7c7b\u578b\uff08\u5982\u5bf9\u8c61\u548c\u6570\u7ec4\uff09\u5f62\u6210\u5bf9\u6bd4\uff0c\u5f15\u7528\u7c7b\u578b\u7684\u503c\u662f\u53ef\u53d8\u7684\u3002<\/p>\n<\/p>\n

\u4e0d\u53ef\u53d8\u6027\u7684\u8bc1\u660e<\/h4>\n<\/p>\n

\u5f53\u4f60\u5728JavaScript\u4e2d\u521b\u5efa\u4e00\u4e2a\u57fa\u672c\u7c7b\u578b\u7684\u53d8\u91cf\u5e76\u8d4b\u503c\uff0c\u8fd9\u4e2a\u503c\u5c31\u88ab\u4fdd\u5b58\u5728\u53d8\u91cf\u4e2d\u3002\u5982\u679c\u5c1d\u8bd5\u4fee\u6539\u8fd9\u4e2a\u503c\uff0c\u89e3\u91ca\u5668\u5b9e\u9645\u4e0a\u4f1a\u521b\u5efa\u4e00\u4e2a\u65b0\u7684\u503c\uff0c\u5e76\u4e14\u5c06\u53d8\u91cf\u7684\u5f15\u7528\u66f4\u65b0\u4e3a\u6307\u5411\u8fd9\u4e2a\u65b0\u503c\u3002\u8001\u7684\u503c\u672c\u8eab\u5e76\u6ca1\u6709\u88ab\u4fee\u6539\uff0c\u800c\u662f\u5728\u6ca1\u6709\u5176\u4ed6\u5f15\u7528\u6307\u5411\u5b83\u65f6\u4f1a\u88ab\u5783\u573e\u56de\u6536\u673a\u5236\u56de\u6536\u3002<\/p>\n<\/p>\n

\u57fa\u672c\u7c7b\u578b\u4e0e\u5185\u5b58<\/h4>\n<\/p>\n

\u57fa\u672c\u7c7b\u578b\u7684\u503c\u5b58\u50a8\u5728\u6808\u5185\u5b58\u4e2d\uff0c\u8fd9\u662f\u4e00\u5757\u66f4\u52a0\u9ad8\u6548\u7684\u5185\u5b58\u533a\u57df\uff0c\u9002\u5408\u5b58\u50a8\u5927\u5c0f\u56fa\u5b9a\u7684\u6570\u636e\u5355\u4f4d\u3002\u6bcf\u6b21\u5bf9\u57fa\u672c\u7c7b\u578b\u7684\u53d8\u91cf\u91cd\u65b0\u8d4b\u503c\uff0c\u5176\u5b9e\u90fd\u662f\u5728\u6808\u5185\u5b58\u4e2d\u653e\u7f6e\u4e86\u4e00\u4e2a\u65b0\u503c\u3002<\/p>\n<\/p>\n

\u4e8c\u3001\u57fa\u672c\u7c7b\u578b\u7684\u64cd\u4f5c\u793a\u4f8b<\/h3>\n<\/p>\n

\u5728JavaScript\u4e2d\uff0c\u5bf9\u57fa\u672c\u7c7b\u578b\u503c\u7684\u64cd\u4f5c\u5f80\u5f80\u7ed9\u4eba\u4e00\u79cd\u503c\u53ef\u4ee5\u53d8\u5316\u7684\u9519\u89c9\uff0c\u4f46\u4e00\u4e2a\u7b80\u5355\u7684\u4f8b\u5b50\u53ef\u4ee5\u8bc1\u660e\u57fa\u672c\u7c7b\u578b\u503c\u7684\u4e0d\u53ef\u53d8\u6027\u3002<\/p>\n<\/p>\n

\u5b57\u7b26\u4e32\u7684\u4e0d\u53ef\u53d8\u6027\u793a\u4f8b<\/h4>\n<\/p>\n

\u8003\u8651\u5982\u4e0b\u5b57\u7b26\u4e32\u64cd\u4f5c\uff1a<\/p>\n<\/p>\n

let greeting = "hello";<\/p>\n
greeting[0] = 'H';<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u5c3d\u7ba1\u770b\u8d77\u6765\u50cf\u662f\u5728\u6539\u53d8greeting<\/code>\u5b57\u7b26\u4e32\u4e2d\u7684\u7b2c\u4e00\u4e2a\u5b57\u6bcd\uff0c\u5b9e\u9645\u4e0a\u6b64\u64cd\u4f5c\u5e76\u4e0d\u4f1a\u6539\u53d8greeting<\/code>\u7684\u503c\u3002\u56e0\u6b64\uff0c\u5f53\u4f60\u5c1d\u8bd5\u6253\u5370greeting<\/code>\u65f6\uff1a<\/p>\n<\/p>\n
console.log(greeting); \/\/ "hello"<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u53ef\u4ee5\u770b\u5230\uff0c\u5b57\u7b26\u4e32\u672c\u8eab\u5e76\u6ca1\u6709\u6539\u53d8\uff0c\u8fd9\u8bc1\u660e\u4e86\u57fa\u672c\u7c7b\u578b\u503c\u7684\u4e0d\u53ef\u53d8\u6027\u3002<\/p>\n<\/p>\n
\u6570\u5b57\u7684\u4e0d\u53ef\u53d8\u6027\u793a\u4f8b<\/h4>\n<\/p>\n
\u4ee5\u6570\u5b57\u4e3a\u4f8b\uff0c\u5f53\u4f60\u5bf9\u4e00\u4e2a\u6570\u5b57\u7c7b\u578b\u7684\u53d8\u91cf\u505a\u52a0\u6cd5\u64cd\u4f5c\u65f6\uff1a<\/p>\n<\/p>\n
let number = 10;<\/p>\n
number += 5;<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u5b9e\u9645\u4e0a\uff0c\u53d8\u91cfnumber<\/code>\u6240\u6307\u5411\u7684\u539f\u59cb\u503c10<\/code>\u5e76\u6ca1\u6709\u6539\u53d8\u3002\u800c\u662f\u521b\u5efa\u4e86\u4e00\u4e2a\u65b0\u7684\u503c15<\/code>\u5e76\u4e14\u66f4\u65b0\u4e86number<\/code>\u7684\u5f15\u7528\u6307\u5411\u3002<\/p>\n<\/p>\n
\u4e09\u3001\u57fa\u672c\u7c7b\u578b\u7684\u6bd4\u8f83<\/h3>\n<\/p>\n
\u57fa\u672c\u7c7b\u578b\u7684\u6bd4\u8f83\u662f\u6839\u636e\u503c\u6765\u8fdb\u884c\u7684\uff0c\u5982\u679c\u4e24\u4e2a\u53d8\u91cf\u7684\u503c\u5b8c\u5168\u76f8\u540c\uff0c\u90a3\u4e48\u8fd9\u4e24\u4e2a\u53d8\u91cf\u5c31\u88ab\u8ba4\u4e3a\u662f\u76f8\u7b49\u7684\u3002<\/p>\n<\/p>\n
\u53d8\u91cf\u4e0e\u503c\u7684\u5bf9\u5e94\u5173\u7cfb<\/h4>\n<\/p>\n
\u57fa\u672c\u7c7b\u578b\u7684\u53d8\u91cf\u76f4\u63a5\u5305\u542b\u5176\u503c\uff0c\u56e0\u6b64\u5f53\u6bd4\u8f83\u4e24\u4e2a\u57fa\u672c\u7c7b\u578b\u7684\u53d8\u91cf\u65f6\uff0c\u4f60\u662f\u5728\u6bd4\u8f83\u5b83\u4eec\u7684\u503c\uff1a<\/p>\n<\/p>\n
let a = 10;<\/p>\n
let b = "10";<\/p>\n
console.log(a == b);  \/\/ \u8f93\u51fa: false<\/p>\n
console.log(a === b); \/\/ \u8f93\u51fa: false<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u5373\u4f7f\u5728\u503c\u4e0a\u770b\u8d77\u6765\u76f8\u4f3c\uff08\u4f8b\u5982\u6570\u5b5710<\/code>\u4e0e\u5b57\u7b26\u4e32"10"<\/code>\uff09\uff0c\u5b83\u4eec\u4e5f\u662f\u4e0d\u540c\u7684\u7c7b\u578b\uff0c\u4e14\u5b58\u50a8\u7684\u503c\u5728\u5e95\u5c42\u662f\u4e0d\u540c\u7684\uff0c\u56e0\u6b64\u5b83\u4eec\u4e0d\u76f8\u7b49\u3002<\/p>\n<\/p>\n
\u4e25\u683c\u7b49\u4e8e\u548c\u62bd\u8c61\u7b49\u4e8e<\/h4>\n<\/p>\n
\u5728\u6bd4\u8f83\u65f6\uff0c==<\/code>\u64cd\u4f5c\u7b26\u4f1a\u6267\u884c\u7c7b\u578b\u8f6c\u6362\uff0c\u800c===<\/code>\u64cd\u4f5c\u7b26\u4e0d\u4f1a\u3002\u8fd9\u610f\u5473\u7740\u4f7f\u7528==<\/code>\u6bd4\u8f83\u65f6\uff0c\u53ef\u80fd\u4f1a\u56e0\u4e3a\u7c7b\u578b\u8f6c\u6362\u5bfc\u81f4\u4e0d\u76f4\u89c2\u7684\u7ed3\u679c\u3002\u56e0\u6b64\uff0c\u63a8\u8350\u4f7f\u7528===<\/code>\u6765\u8fdb\u884c\u6bd4\u8f83\uff0c\u56e0\u4e3a\u8fd9\u53ef\u4ee5\u907f\u514d\u7c7b\u578b\u8f6c\u6362\u5bfc\u81f4\u7684\u6df7\u6dc6\u3002<\/p>\n<\/p>\n
\u56db\u3001\u5f15\u7528\u7c7b\u578b\u7684\u53ef\u53d8\u6027\u6bd4\u8f83<\/h3>\n<\/p>\n
\u4e0e\u57fa\u672c\u7c7b\u578b\u7684\u4e0d\u53ef\u53d8\u6027\u5f62\u6210\u5bf9\u6bd4\u7684\u662f\uff0cJavaScript\u4e2d\u7684\u5f15\u7528\u7c7b\u578b\uff08\u5982\u5bf9\u8c61\u548c\u6570\u7ec4\uff09\u662f\u53ef\u53d8\u7684\u3002\u5f15\u7528\u7c7b\u578b\u7684\u503c\u5b9e\u9645\u4e0a\u662f\u5bf9\u8c61\u6216\u6570\u636e\u7ed3\u6784\u7684\u5f15\u7528\uff0c\u800c\u4e0d\u662f\u6570\u636e\u672c\u8eab\u3002<\/p>\n<\/p>\n
\u5bf9\u8c61\u7684\u53ef\u53d8\u6027<\/h4>\n<\/p>\n
\u521b\u5efa\u5bf9\u8c61\u540e\uff0c\u53ef\u4ee5\u968f\u65f6\u6dfb\u52a0\u3001\u4fee\u6539\u6216\u5220\u9664\u5176\u5c5e\u6027\uff1a<\/p>\n<\/p>\n
let user = { name: "John" };<\/p>\n
user.name = "Jane"; \/\/ \u4fee\u6539\u5c5e\u6027<\/p>\n
user.age = 30; \/\/ \u6dfb\u52a0\u5c5e\u6027<\/p>\n
delete user.name; \/\/ \u5220\u9664\u5c5e\u6027<\/p>\n
console.log(user); \/\/ { age: 30 }<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u5728\u4e0a\u8ff0\u793a\u4f8b\u4e2d\uff0c\u5bf9\u8c61user<\/code>\u6240\u5f15\u7528\u7684\u5185\u5bb9\u662f\u53ef\u4ee5\u6539\u53d8\u7684\u3002\u6211\u4eec\u5e76\u4e0d\u662f\u521b\u5efa\u4e86\u4e00\u4e2a\u65b0\u7684\u5bf9\u8c61\uff0c\u800c\u662f\u6539\u53d8\u4e86user<\/code>\u6240\u5f15\u7528\u7684\u90a3\u4e2a\u5bf9\u8c61\u7684\u5185\u5bb9\u3002<\/p>\n<\/p>\n
\u6570\u7ec4\u7684\u53ef\u53d8\u6027<\/h4>\n<\/p>\n
\u5bf9\u4e8e\u6570\u7ec4\u800c\u8a00\uff0c\u540c\u6837\u4e5f\u53ef\u4ee5\u5728\u521b\u5efa\u4e4b\u540e\u4fee\u6539\u5176\u5185\u5bb9\uff1a<\/p>\n<\/p>\n
let numbers = [1, 2, 3];<\/p>\n
numbers.push(4); \/\/ \u5411\u6570\u7ec4\u6dfb\u52a0\u5143\u7d20<\/p>\n
numbers[0] = 10; \/\/ \u4fee\u6539\u6570\u7ec4\u5143\u7d20<\/p>\n
console.log(numbers); \/\/ [10, 2, 3, 4]<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u53ef\u4ee5\u770b\u5230\uff0c\u6570\u7ec4numbers<\/code>\u7684\u5185\u5bb9\u88ab\u6539\u53d8\u4e86\u3002\u8fd9\u8bf4\u660e\u5f15\u7528\u7c7b\u578b\u7684\u503c\u662f\u53ef\u53d8\u7684\u3002<\/p>\n<\/p>\n
\u4e94\u3001\u603b\u7ed3<\/h3>\n<\/p>\n
\u603b\u800c\u8a00\u4e4b\uff0cJavaScript\u4e2d\u57fa\u672c\u7c7b\u578b\u503c\u7684\u4e0d\u53ef\u53d8\u6027\u548c\u5f15\u7528\u7c7b\u578b\u503c\u7684\u53ef\u53d8\u6027\u662fJavaScript\u6570\u636e\u7ba1\u7406\u7684\u6838\u5fc3\u7279\u5f81\u4e4b\u4e00\u3002\u8fd9\u79cd\u533a\u5206\u5728\u5904\u7406\u4e0d\u540c\u6570\u636e\u7c7b\u578b\u65f6\uff0c\u51b3\u5b9a\u4e86\u53d8\u91cf\u8d4b\u503c\u3001\u64cd\u4f5c\u4ee5\u53ca\u6bd4\u8f83\u7684\u884c\u4e3a\uff0c\u662f\u7f16\u7a0b\u4e2d\u9700\u8981\u7406\u89e3\u548c\u8003\u8651\u7684\u91cd\u8981\u6982\u5ff5\u3002<\/p>\n<\/p>\n
\u76f8\u5173\u95ee\u7b54FAQs\uff1a<\/strong><\/h2>\n
1. JavaScript\u7684\u57fa\u672c\u7c7b\u578b\u503c\u662f\u53ef\u53d8\u7684\u5417\uff1f<\/strong>
\n\u867d\u7136JavaScript\u7684\u57fa\u672c\u7c7b\u578b\u503c\uff08\u5982\u5b57\u7b26\u4e32\u3001\u6570\u5b57\u3001\u5e03\u5c14\u503c\u3001undefined\u548cnull\uff09\u662f\u4e0d\u53ef\u53d8\u7684\uff0c\u4f46\u8fd9\u5e76\u4e0d\u610f\u5473\u7740\u5b83\u4eec\u4e0d\u80fd\u88ab\u4fee\u6539\u3002\u5f53\u6211\u4eec\u5bf9\u57fa\u672c\u7c7b\u578b\u7684\u503c\u8fdb\u884c\u64cd\u4f5c\u65f6\uff0c\u5b9e\u9645\u4e0a\u662f\u521b\u5efa\u4e86\u4e00\u4e2a\u65b0\u7684\u503c\uff0c\u800c\u4e0d\u662f\u4fee\u6539\u539f\u59cb\u7684\u503c\u3002<\/p>\n
2. JavaScript\u4e2d\u57fa\u672c\u7c7b\u578b\u7684\u503c\u5982\u4f55\u8fdb\u884c\u4fee\u6539\uff1f<\/strong>
\n\u867d\u7136\u57fa\u672c\u7c7b\u578b\u7684\u503c\u662f\u4e0d\u53ef\u53d8\u7684\uff0c\u4f46\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7\u8d4b\u4e88\u65b0\u503c\u7684\u65b9\u5f0f\u6765\u4fee\u6539\u5b83\u4eec\u3002\u4f8b\u5982\uff0c\u6211\u4eec\u53ef\u4ee5\u5c06\u4e00\u4e2a\u5b57\u7b26\u4e32\u7684\u503c\u8d4b\u7ed9\u53e6\u4e00\u4e2a\u5b57\u7b26\u4e32\u53d8\u91cf\uff0c\u4ece\u800c\u4fee\u6539\u5b57\u7b26\u4e32\u7684\u503c\u3002\u8fd9\u5b9e\u9645\u4e0a\u662f\u521b\u5efa\u4e86\u4e00\u4e2a\u65b0\u7684\u5b57\u7b26\u4e32\uff0c\u800c\u539f\u59cb\u5b57\u7b26\u4e32\u4ecd\u7136\u4fdd\u6301\u4e0d\u53d8\u3002<\/p>\n
3. \u4e3a\u4ec0\u4e48\u8bf4JavaScript\u7684\u57fa\u672c\u7c7b\u578b\u503c\u662f\u4e0d\u53ef\u53d8\u7684\uff1f<\/strong>
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