{"id":168228,"date":"2024-05-08T16:19:31","date_gmt":"2024-05-08T08:19:31","guid":{"rendered":"https:\/\/docs.pingcode.com\/ask\/ask-ask\/168228.html"},"modified":"2024-05-08T16:19:36","modified_gmt":"2024-05-08T08:19:36","slug":"javascript-%e4%b8%ad-switch-%e7%9a%84%e5%86%99%e6%b3%95%e6%9c%89%e5%93%aa%e4%ba%9b","status":"publish","type":"post","link":"https:\/\/docs.pingcode.com\/ask\/168228.html","title":{"rendered":"JavaScript \u4e2d switch \u7684\u5199\u6cd5\u6709\u54ea\u4e9b"},"content":{"rendered":"

\"JavaScript<\/p>\n

JavaScript \u4e2d\u7684 switch<\/code> \u8bed\u53e5\u662f\u4e00\u79cd\u6761\u4ef6\u8bed\u53e5\uff0c\u5b83\u7528\u4e8e\u6267\u884c\u4e0d\u540c\u7684\u4ee3\u7801\u5757\u57fa\u4e8e\u4e0d\u540c\u7684\u6761\u4ef6\u3002\u5728JavaScript\u4e2d\uff0cswitch<\/code> \u7684\u5199\u6cd5\u4e3b\u8981\u6709\u4e24\u79cd\uff0c\u4f7f\u7528\u5355\u4e2a\u6761\u4ef6\u5206\u652f<\/strong>\u3001\u4f7f\u7528\u591a\u4e2a\u6761\u4ef6\u5171\u4eab\u540c\u4e00\u4ee3\u7801\u5757<\/strong>\u3002\u7279\u522b\u5730\uff0c\u4f7f\u7528\u591a\u4e2a\u6761\u4ef6\u5171\u4eab\u540c\u4e00\u4ee3\u7801\u5757\u7684\u5199\u6cd5<\/strong>\uff0c\u4e3a\u4ee3\u7801\u7684\u590d\u7528\u548c\u7b80\u6d01\u6027\u63d0\u4f9b\u4e86\u5f88\u597d\u7684\u652f\u6301\u3002<\/p>\n<\/p>\n

\u4e00\u3001\u4f7f\u7528\u5355\u4e2a\u6761\u4ef6\u5206\u652f<\/h3>\n<\/p>\n

\u6b64\u79cd\u5199\u6cd5\u662f switch<\/code> \u8bed\u53e5\u6700\u57fa\u672c\u7684\u5f62\u5f0f\uff0c\u5b83\u9488\u5bf9\u67d0\u4e2a\u53d8\u91cf\u6216\u8868\u8fbe\u5f0f\u7684\u4e0d\u540c\u503c\u6267\u884c\u4e0d\u540c\u7684\u4ee3\u7801\u8def\u5f84\u3002<\/p>\n<\/p>\n

let fruit = 'apple';<\/p>\n
switch (fruit) {<\/p>\n
  case 'apple':<\/p>\n
    console.log('Apple is red');<\/p>\n
    break;<\/p>\n
  case 'banana':<\/p>\n
    console.log('Banana is yellow');<\/p>\n
    break;<\/p>\n
  default:<\/p>\n
    console.log('Unknown fruit');<\/p>\n
}<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0cswitch<\/code> \u8bed\u53e5\u68c0\u67e5 fruit<\/code> \u53d8\u91cf\u7684\u503c\u3002\u5bf9\u4e8e\u6bcf\u4e2a case<\/code> \u5173\u952e\u5b57\uff0c\u5982\u679c\u53d8\u91cf\u7684\u503c\u4e0e case<\/code> \u540e\u7684\u503c\u76f8\u5339\u914d\uff0c\u76f8\u5e94\u7684\u4ee3\u7801\u5757\u5c31\u4f1a\u88ab\u6267\u884c\u3002\u5982\u679c\u6ca1\u6709\u4efb\u4f55 case<\/code> \u503c\u4e0e\u53d8\u91cf\u7684\u503c\u5339\u914d\uff0cdefault<\/code> \u5173\u952e\u5b57\u540e\u7684\u4ee3\u7801\u5757\u4f1a\u88ab\u6267\u884c\u3002<\/p>\n<\/p>\n
\u4e8c\u3001\u4f7f\u7528\u591a\u4e2a\u6761\u4ef6\u5171\u4eab\u540c\u4e00\u4ee3\u7801\u5757<\/h3>\n<\/p>\n
\u8fd9\u79cd\u5199\u6cd5\u9002\u7528\u4e8e\u591a\u4e2a\u6761\u4ef6\u9700\u8981\u6267\u884c\u76f8\u540c\u64cd\u4f5c\u7684\u60c5\u51b5\uff0c\u53ef\u4ee5\u901a\u8fc7\u7701\u7565 break<\/code> \u8bed\u53e5\u6765\u5b9e\u73b0\u3002<\/p>\n<\/p>\n
let color = 'red';<\/p>\n
switch (color) {<\/p>\n
  case 'red':<\/p>\n
  case 'pink':<\/p>\n
    console.log('The color is a shade of red');<\/p>\n
    break;<\/p>\n
  case 'blue':<\/p>\n
  case 'light blue':<\/p>\n
    console.log('The color is a shade of blue');<\/p>\n
    break;<\/p>\n
  default:<\/p>\n
    console.log('Unknown color');<\/p>\n
}<\/p>\n
<\/code><\/pre>\n<\/p>\n
\u5728\u4e0a\u8ff0\u4ee3\u7801\u4e2d\uff0c\u5982\u679c color<\/code> \u662f 'red'<\/code> \u6216 'pink'<\/code>\uff0c\u540c\u4e00\u6761\u6d88\u606f 'The color is a shade of red'<\/code> \u88ab\u6253\u5370\u51fa\u6765\u3002\u8fd9\u79cd\u65b9\u6cd5\u907f\u514d\u4e86\u4ee3\u7801\u91cd\u590d\uff0c\u589e\u52a0\u4e86\u4ee3\u7801\u7684\u53ef\u8bfb\u6027\u548c\u53ef\u7ef4\u62a4\u6027\u3002<\/p>\n<\/p>\n
\u4e09\u3001\u6ce8\u610f\u4e8b\u9879<\/h3>\n<\/p>\n
\u5728\u4f7f\u7528 switch<\/code> \u8bed\u53e5\u65f6\uff0c\u6709\u51e0\u4e2a\u91cd\u8981\u70b9\u9700\u8981\u6ce8\u610f\uff1a<\/p>\n<\/p>\n
    \n
  • break<\/code> \u8bed\u53e5\u7684\u4f7f\u7528<\/strong>\uff1a\u5728\u6bcf\u4e2a case<\/code> \u540e\u4f7f\u7528 break<\/code> \u8bed\u53e5\u53ef\u4ee5\u9632\u6b62 switch<\/code> \u8bed\u53e5\u7ee7\u7eed\u6267\u884c\u540e\u7eed\u7684 case<\/code>\uff0c\u4ece\u800c\u907f\u514d\u4e0d\u5fc5\u8981\u7684\u9519\u8bef\u3002<\/li>\n
  • default<\/code> \u5173\u952e\u5b57\u7684\u4f5c\u7528<\/strong>\uff1adefault<\/code> \u5173\u952e\u5b57\u7528\u4e8e\u5339\u914d\u6240\u6709\u672a\u88ab\u4e4b\u524d\u7684 case<\/code> \u6355\u83b7\u7684\u503c\u3002\u5efa\u8bae\u603b\u662f\u5728 switch<\/code> \u8bed\u53e5\u7684\u6700\u540e\u52a0\u4e0a default<\/code> \u5206\u652f\uff0c\u5373\u4f7f\u5b83\u53ea\u662f\u6253\u5370\u4e00\u4e2a\u9519\u8bef\u6d88\u606f\u3002<\/li>\n
  • \u6bd4\u8f83\u4e25\u683c\u6027<\/strong>\uff1aswitch<\/code> \u8bed\u53e5\u4f7f\u7528 ===<\/code> \u8fdb\u884c\u6bd4\u8f83\uff0c\u8fd9\u610f\u5473\u7740\u503c\u548c\u7c7b\u578b\u90fd\u5fc5\u987b\u76f8\u540c\u3002<\/li>\n<\/ul>\n
    \u56db\u3001\u5bf9\u6bd4 if-else \u8bed\u53e5<\/h3>\n<\/p>\n
    \u4e0e if-else<\/code> \u8bed\u53e5\u76f8\u6bd4\uff0cswitch<\/code> \u5728\u5904\u7406\u591a\u6761\u4ef6\u5206\u652f\u65f6\u901a\u5e38\u66f4\u4e3a\u6e05\u6670\u548c\u6613\u8bfb\u3002\u4f46\u662f\uff0cswitch<\/code> \u8bed\u53e5\u53ea\u80fd\u5bf9\u540c\u4e00\u4e2a\u8868\u8fbe\u5f0f\u6216\u53d8\u91cf\u8fdb\u884c\u591a\u6b21\u6761\u4ef6\u5224\u65ad\uff0c\u800c if-else<\/code> \u53ef\u4ee5\u5728\u6bcf\u4e2a\u6761\u4ef6\u5206\u652f\u4e2d\u4f7f\u7528\u4e0d\u540c\u7684\u8868\u8fbe\u5f0f\u3002<\/p>\n<\/p>\n
    \u4e94\u3001\u5b9e\u8df5\u5efa\u8bae<\/h3>\n<\/p>\n
      \n
    • \u5f53\u4f60\u6709\u4e00\u4e2a\u53d8\u91cf\u9700\u8981\u4e0e\u591a\u4e2a\u53ef\u80fd\u7684\u503c\u8fdb\u884c\u6bd4\u8f83\u65f6\uff0c\u4f7f\u7528 switch<\/code> \u8bed\u53e5\u3002<\/li>\n
    • \u5c3d\u53ef\u80fd\u4f7f\u7528 default<\/code> \u8bed\u53e5\u6765\u5904\u7406\u672a\u77e5\u7684\u6216\u610f\u5916\u7684\u503c\u3002<\/li>\n
    • \u5728\u9002\u5f53\u7684\u60c5\u51b5\u4e0b\u91cd\u7528\u4ee3\u7801\u5757\uff0c\u51cf\u5c11\u4ee3\u7801\u91cd\u590d\uff0c\u4f8b\u5982\u901a\u8fc7\u8ba9\u591a\u4e2a case<\/code> \u6807\u7b7e\u5171\u4eab\u540c\u4e00\u4e2a\u4ee3\u7801\u5757\u3002<\/li>\n<\/ul>\n
      \u603b\u4f53\u800c\u8a00\uff0cswitch<\/code> \u8bed\u53e5\u662fJavaScript\u4e2d\u5904\u7406\u57fa\u4e8e\u591a\u4e2a\u6761\u4ef6\u7684\u5206\u652f\u903b\u8f91\u7684\u5f3a\u5927\u5de5\u5177\u3002\u5408\u7406\u4f7f\u7528 switch<\/code> \u8bed\u53e5\u53ef\u4ee5\u4f7f\u4ee3\u7801\u66f4\u52a0\u6e05\u6670\u3001\u7b80\u6d01\u548c\u6613\u4e8e\u7ef4\u62a4\u3002<\/p>\n<\/p>\n
      \u76f8\u5173\u95ee\u7b54FAQs\uff1a<\/strong><\/h2>\n
      1. JavaScript \u4e2d switch \u7684\u8bed\u6cd5\u683c\u5f0f\u662f\u600e\u6837\u7684\uff1f<\/strong>
      \n\u5728 JavaScript \u4e2d\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528 switch \u8bed\u53e5\u6765\u6839\u636e\u4e00\u4e2a\u8868\u8fbe\u5f0f\u7684\u503c\uff0c\u6267\u884c\u4e0d\u540c\u7684\u4ee3\u7801\u5757\u3002switch \u8bed\u53e5\u7684\u57fa\u672c\u8bed\u6cd5\u683c\u5f0f\u5982\u4e0b\uff1a<\/p>\n
      switch(expression) {\n  case value1:\n    \/\/ \u5f53 expression \u7b49\u4e8e value1 \u65f6\u6267\u884c\u7684\u4ee3\u7801\n    break;\n  case value2:\n    \/\/ \u5f53 expression \u7b49\u4e8e value2 \u65f6\u6267\u884c\u7684\u4ee3\u7801\n    break;\n  ...\n  default:\n    \/\/ \u5f53 expression \u4e0e\u4ee5\u4e0a\u6240\u6709\u7684\u503c\u90fd\u4e0d\u5339\u914d\u65f6\u6267\u884c\u7684\u4ee3\u7801\n}\n<\/code><\/pre>\n
      2. switch \u8bed\u53e5\u53ef\u4ee5\u5904\u7406\u54ea\u4e9b\u7c7b\u578b\u7684\u6570\u636e\uff1f<\/strong>
      \nswitch \u8bed\u53e5\u53ef\u4ee5\u5904\u7406\u5404\u79cd\u7c7b\u578b\u7684\u6570\u636e\uff0c\u5305\u62ec\u6570\u5b57\u3001\u5b57\u7b26\u4e32\u4ee5\u53ca\u5e03\u5c14\u503c\u7b49\u3002\u5728 switch \u8bed\u53e5\u4e2d\uff0c\u8868\u8fbe\u5f0f\u7684\u503c\u4f1a\u4e0e\u5404\u4e2a case \u7684\u503c\u8fdb\u884c\u6bd4\u8f83\uff0c\u76f4\u5230\u627e\u5230\u5339\u914d\u7684\u503c\u4e3a\u6b62\u3002\u6bd4\u8f83\u65f6\u4f1a\u4f7f\u7528\u4e25\u683c\u76f8\u7b49\u8fd0\u7b97\u7b26\uff08===\uff09\uff0c\u56e0\u6b64\u9700\u8981\u786e\u4fdd\u6bd4\u8f83\u7684\u6570\u636e\u7c7b\u578b\u76f8\u540c\u3002<\/p>\n
      3. \u662f\u5426\u53ef\u4ee5\u5728 switch \u8bed\u53e5\u4e2d\u7701\u7565 break \u5173\u952e\u5b57\uff1f<\/strong>
      \n\u5728 switch \u8bed\u53e5\u4e2d\uff0c\u6bcf\u4e2a case \u540e\u9762\u901a\u5e38\u4f1a\u8ddf\u7740\u4e00\u4e2a break \u5173\u952e\u5b57\uff0c\u7528\u4e8e\u7ec8\u6b62\u5f53\u524d\u7684\u4ee3\u7801\u5757\u5e76\u8df3\u51fa switch \u8bed\u53e5\u3002\u4e0d\u8fc7\uff0c\u6709\u65f6\u5019\u6211\u4eec\u4e5f\u53ef\u4ee5\u7701\u7565 break \u5173\u952e\u5b57\uff0c\u4f7f\u4ee3\u7801\u6267\u884c\u7a7f\u900f\u5230\u4e0b\u4e00\u4e2a case \u4e2d\u7684\u4ee3\u7801\u5757\u3002\u8fd9\u79cd\u60c5\u51b5\u901a\u5e38\u7528\u4e8e\u4e00\u4e9b\u7279\u5b9a\u7684\u9700\u6c42\uff0c\u4f46\u9700\u8981\u6ce8\u610f\u63a7\u5236\u4ee3\u7801\u903b\u8f91\uff0c\u907f\u514d\u4ea7\u751f\u610f\u5916\u7684\u7ed3\u679c\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"JavaScript \u4e2d\u7684 switch \u8bed\u53e5\u662f\u4e00\u79cd\u6761\u4ef6\u8bed\u53e5\uff0c\u5b83\u7528\u4e8e\u6267\u884c\u4e0d\u540c\u7684\u4ee3\u7801\u5757\u57fa\u4e8e\u4e0d\u540c\u7684\u6761\u4ef6\u3002\u5728Java […]","protected":false},"author":3,"featured_media":168234,"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\/168228"}],"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=168228"}],"version-history":[{"count":0,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/168228\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media\/168234"}],"wp:attachment":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media?parent=168228"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/categories?post=168228"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/tags?post=168228"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}