{"id":2042,"date":"2025-02-25T22:51:10","date_gmt":"2025-02-25T14:51:10","guid":{"rendered":"https:\/\/www.laixuexila.com\/?p=2042"},"modified":"2025-02-25T22:51:10","modified_gmt":"2025-02-25T14:51:10","slug":"javascript-for-%e5%be%aa%e7%8e%af","status":"publish","type":"post","link":"https:\/\/www.laixuexila.com\/index.php\/2025\/02\/25\/javascript-for-%e5%be%aa%e7%8e%af\/","title":{"rendered":"JavaScript\u00a0for \u5faa\u73af"},"content":{"rendered":"\n

\u4e00\u3001JavaScript for<\/code> \u5faa\u73af<\/strong><\/h3>\n\n\n\n

for<\/code> \u5faa\u73af\u662f JavaScript \u4e2d\u5e38\u7528\u7684\u63a7\u5236\u6d41\u8bed\u53e5\uff0c\u7528\u4e8e\u91cd\u590d\u6267\u884c\u4e00\u6bb5\u4ee3\u7801\uff0c\u76f4\u5230\u6ee1\u8db3\u6307\u5b9a\u7684\u6761\u4ef6\u3002\u5b83\u901a\u5e38\u7528\u4e8e\u9700\u8981\u91cd\u590d\u6267\u884c\u56fa\u5b9a\u6b21\u6570\u7684\u60c5\u51b5\u3002<\/p>\n\n\n\n

\u57fa\u672c\u8bed\u6cd5<\/strong><\/h4>\n\n\n\n
for (initialization; condition; increment\/decrement) {\n    \/\/ \u5faa\u73af\u4f53\uff0c\u6267\u884c\u7684\u4ee3\u7801\n}<\/code><\/pre>\n\n\n\n
    \n
  • initialization<\/code>\uff1a\u521d\u59cb\u5316\u90e8\u5206\uff0c\u901a\u5e38\u7528\u4e8e\u58f0\u660e\u5e76\u8bbe\u7f6e\u8ba1\u6570\u5668\u53d8\u91cf\u3002<\/li>\n\n\n\n
  • condition<\/code>\uff1a\u5faa\u73af\u6761\u4ef6\uff0c\u5224\u65ad\u5faa\u73af\u662f\u5426\u7ee7\u7eed\u3002\u6bcf\u6b21\u8fed\u4ee3\u524d\uff0c\u90fd\u4f1a\u68c0\u67e5\u6b64\u6761\u4ef6\uff0c\u53ea\u6709\u6761\u4ef6\u4e3a true<\/code> \u65f6\uff0c\u5faa\u73af\u624d\u4f1a\u7ee7\u7eed\u3002<\/li>\n\n\n\n
  • increment\/decrement<\/code>\uff1a\u6bcf\u6b21\u8fed\u4ee3\u540e\u66f4\u65b0\u8ba1\u6570\u5668\u53d8\u91cf\uff0c\u901a\u5e38\u662f\u81ea\u589e\uff08i++<\/code>\uff09\u6216\u81ea\u51cf\uff08i--<\/code>\uff09\u3002<\/li>\n<\/ul>\n\n\n\n
    \u793a\u4f8b\uff1a\u57fa\u7840\u7684 for<\/code> \u5faa\u73af<\/strong><\/h4>\n\n\n\n
    for (let i = 0; i < 5; i++) {\n    console.log(i);\n}<\/code><\/pre>\n\n\n\n
    \u8f93\u51fa\uff1a<\/p>\n\n\n\n
    0\n1\n2\n3\n4<\/code><\/pre>\n\n\n\n
    \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0ci<\/code> \u4ece 0 \u5f00\u59cb\uff0c\u6bcf\u6b21\u5faa\u73af i<\/code> \u81ea\u589e 1\uff0c\u76f4\u5230 i<\/code> \u4e0d\u518d\u5c0f\u4e8e 5 \u65f6\u505c\u6b62\u5faa\u73af\u3002<\/p>\n\n\n\n
    \u5faa\u73af\u6d41\u7a0b\u5206\u6790<\/strong><\/h4>\n\n\n\n
      \n
    1. initialization<\/code>\uff1alet i = 0<\/code>\u3002\u521d\u59cb\u5316\u53d8\u91cf i<\/code> \u4e3a 0\u3002<\/li>\n\n\n\n
    2. condition<\/code>\uff1ai < 5<\/code>\u3002\u6bcf\u6b21\u6267\u884c\u524d\u68c0\u67e5\u662f\u5426\u6ee1\u8db3\u6761\u4ef6\uff0c\u5982\u679c\u6ee1\u8db3\u7ee7\u7eed\u6267\u884c\uff0c\u5426\u8005\u8df3\u51fa\u5faa\u73af\u3002<\/li>\n\n\n\n
    3. increment\/decrement<\/code>\uff1ai++<\/code>\u3002\u6bcf\u6b21\u5faa\u73af\u7ed3\u675f\u540e\uff0ci<\/code> \u7684\u503c\u52a0 1\u3002<\/li>\n<\/ol>\n\n\n\n
      \n\n\n\n
      \u4e8c\u3001for<\/code> \u5faa\u73af\u7684\u5176\u4ed6\u5e94\u7528<\/strong><\/h3>\n\n\n\n
      \u5012\u5e8f\u5faa\u73af<\/strong><\/h4>\n\n\n\n
      for<\/code> \u5faa\u73af\u53ef\u4ee5\u7528\u6765\u5012\u5e8f\u904d\u5386\u6570\u7ec4\u6216\u5176\u4ed6\u53ef\u8fed\u4ee3\u5bf9\u8c61\u3002\u901a\u8fc7\u8c03\u6574 i<\/code> \u7684\u521d\u59cb\u503c\u548c\u6761\u4ef6\uff0c\u4f60\u53ef\u4ee5\u5b9e\u73b0\u4ece\u5927\u5230\u5c0f\u7684\u5faa\u73af\u3002<\/p>\n\n\n\n
      for (let i = 5; i >= 0; i--) {\n    console.log(i);\n}<\/code><\/pre>\n\n\n\n
      \u8f93\u51fa\uff1a<\/p>\n\n\n\n
      5\n4\n3\n2\n1\n0<\/code><\/pre>\n\n\n\n
      \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0ci<\/code> \u4ece 5 \u5f00\u59cb\uff0c\u6bcf\u6b21\u81ea\u51cf\uff0c\u76f4\u5230 i<\/code> \u4e0d\u518d\u5927\u4e8e\u7b49\u4e8e 0\u3002<\/p>\n\n\n\n
      \u5faa\u73af\u904d\u5386\u6570\u7ec4<\/strong><\/h4>\n\n\n\n
      \u4f7f\u7528 for<\/code> \u5faa\u73af\u904d\u5386\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e2a\u5143\u7d20\u662f\u4e00\u4e2a\u5e38\u89c1\u7684\u7528\u6cd5\u3002<\/p>\n\n\n\n
      let fruits = [\"apple\", \"banana\", \"cherry\", \"date\"];\n\nfor (let i = 0; i < fruits.length; i++) {\n    console.log(fruits[i]);\n}<\/code><\/pre>\n\n\n\n
      \u8f93\u51fa\uff1a<\/p>\n\n\n\n
      apple\nbanana\ncherry\ndate<\/code><\/pre>\n\n\n\n
      \u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0cfruits.length<\/code> \u83b7\u53d6\u6570\u7ec4\u7684\u957f\u5ea6\uff0c\u7136\u540e\u901a\u8fc7 i<\/code> \u4f9d\u6b21\u904d\u5386\u6570\u7ec4\u4e2d\u7684\u6bcf\u4e2a\u5143\u7d20\u3002<\/p>\n\n\n\n
      \n\n\n\n
      \u4e09\u3001for...in<\/code> \u5faa\u73af<\/strong><\/h3>\n\n\n\n
      for...in<\/code> \u5faa\u73af\u662f\u4e13\u95e8\u7528\u6765\u904d\u5386\u5bf9\u8c61\u5c5e\u6027\u7684\u3002\u5b83\u53ef\u4ee5\u7528\u6765\u5faa\u73af\u5bf9\u8c61\u7684\u952e\uff08property keys\uff09\u3002<\/p>\n\n\n\n
      \u8bed\u6cd5<\/strong><\/h4>\n\n\n\n
      for (let key in object) {\n    \/\/ \u6267\u884c\u4ee3\u7801\uff0ckey \u662f\u5bf9\u8c61\u7684\u5c5e\u6027\u540d\n}<\/code><\/pre>\n\n\n\n
      \u793a\u4f8b\uff1a\u904d\u5386\u5bf9\u8c61\u7684\u5c5e\u6027<\/strong><\/h4>\n\n\n\n
      let person = {\n    name: \"Alice\",\n    age: 25,\n    city: \"New York\"\n};\n\nfor (let key in person) {\n    console.log(key + \": \" + person[key]);\n}<\/code><\/pre>\n\n\n\n
      \u8f93\u51fa\uff1a<\/p>\n\n\n\n
      name: Alice\nage: 25\ncity: New York<\/code><\/pre>\n\n\n\n
      \u5728\u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0cfor...in<\/code> \u5faa\u73af\u904d\u5386\u4e86 person<\/code> \u5bf9\u8c61\u7684\u6bcf\u4e2a\u5c5e\u6027\uff0c\u5e76\u901a\u8fc7 person[key]<\/code> \u83b7\u53d6\u5c5e\u6027\u7684\u503c\u3002<\/p>\n\n\n\n
      \n\n\n\n
      \u56db\u3001for...of<\/code> \u5faa\u73af<\/strong><\/h3>\n\n\n\n
      for...of<\/code> \u5faa\u73af\u662f\u4e13\u95e8\u7528\u6765\u904d\u5386\u53ef\u8fed\u4ee3\u5bf9\u8c61\uff08\u5982\u6570\u7ec4\u3001\u5b57\u7b26\u4e32\u3001Map\u3001Set \u7b49\uff09\u5143\u7d20\u7684\u3002\u5b83\u4e0e for...in<\/code> \u4e0d\u540c\uff0cfor...of<\/code> \u904d\u5386\u7684\u662f\u5bf9\u8c61\u7684\u503c\uff0c\u800c\u4e0d\u662f\u952e\u3002<\/p>\n\n\n\n
      \u8bed\u6cd5<\/strong><\/h4>\n\n\n\n
      for (let value of iterable) {\n    \/\/ \u6267\u884c\u4ee3\u7801\uff0cvalue \u662f\u53ef\u8fed\u4ee3\u5bf9\u8c61\u7684\u5143\u7d20\n}<\/code><\/pre>\n\n\n\n
      \u793a\u4f8b\uff1a\u904d\u5386\u6570\u7ec4\u5143\u7d20<\/strong><\/h4>\n\n\n\n
      let fruits = [\"apple\", \"banana\", \"cherry\"];\n\nfor (let fruit of fruits) {\n    console.log(fruit);\n}<\/code><\/pre>\n\n\n\n
      \u8f93\u51fa\uff1a<\/p>\n\n\n\n
      apple\nbanana\ncherry<\/code><\/pre>\n\n\n\n
      \u8fd9\u4e2a\u4f8b\u5b50\u4e2d\uff0cfor...of<\/code> \u904d\u5386\u4e86 fruits<\/code> \u6570\u7ec4\u4e2d\u7684\u6bcf\u4e2a\u5143\u7d20\uff0c\u5e76\u8f93\u51fa\u5b83\u4eec\u3002<\/p>\n\n\n\n
      \n\n\n\n
      \u603b\u7ed3<\/strong><\/h3>\n\n\n\n
        \n
      • for<\/code> \u5faa\u73af<\/strong>\uff1a\u7528\u4e8e\u5faa\u73af\u6267\u884c\u56fa\u5b9a\u6b21\u6570\u7684\u4ee3\u7801\uff0c\u9002\u5408\u7528\u4e8e\u5df2\u77e5\u6b21\u6570\u7684\u5faa\u73af\u3002<\/li>\n\n\n\n
      • for...in<\/code> \u5faa\u73af<\/strong>\uff1a\u7528\u4e8e\u904d\u5386\u5bf9\u8c61\u7684\u5c5e\u6027\uff0c\u83b7\u53d6\u6bcf\u4e2a\u5c5e\u6027\u540d\u3002<\/li>\n\n\n\n
      • for...of<\/code> \u5faa\u73af<\/strong>\uff1a\u7528\u4e8e\u904d\u5386\u53ef\u8fed\u4ee3\u5bf9\u8c61\u7684\u5143\u7d20\uff08\u5982\u6570\u7ec4\u3001\u5b57\u7b26\u4e32\u3001Map\u3001Set \u7b49\uff09\uff0c\u9002\u5408\u904d\u5386\u6570\u7ec4\u548c\u5b57\u7b26\u4e32\u7b49\u3002<\/li>\n<\/ul>\n\n\n\n
        for<\/code> \u5faa\u73af\u662f JavaScript \u4e2d\u6700\u57fa\u7840\u4e14\u5f3a\u5927\u7684\u63a7\u5236\u6d41\u5de5\u5177\u4e4b\u4e00\uff0c\u80fd\u591f\u5e2e\u52a9\u6211\u4eec\u9ad8\u6548\u5730\u8fdb\u884c\u91cd\u590d\u64cd\u4f5c\u3002\u66f4\u591a\u76f8\u5173\u5185\u5bb9\u8bf7\u5173\u6ce8\u5176\u4ed6\u76f8\u5173\u6587\u7ae0\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"
        \u4e00\u3001JavaScript for \u5faa\u73af for \u5faa\u73af\u662f JavaScript \u4e2d\u5e38\u7528\u7684\u63a7\u5236\u6d41\u8bed\u53e5\uff0c\u7528\u4e8e\u91cd\u590d\u6267\u884c […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[46],"tags":[],"class_list":["post-2042","post","type-post","status-publish","format-standard","hentry","category-javascript"],"_links":{"self":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2042","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/comments?post=2042"}],"version-history":[{"count":1,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2042\/revisions"}],"predecessor-version":[{"id":2043,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/posts\/2042\/revisions\/2043"}],"wp:attachment":[{"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/media?parent=2042"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/categories?post=2042"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.laixuexila.com\/index.php\/wp-json\/wp\/v2\/tags?post=2042"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}