{"id":639,"date":"2019-11-25T10:39:40","date_gmt":"2019-11-25T02:39:40","guid":{"rendered":"http:\/\/blog.xrhoujie.com\/?p=639"},"modified":"2019-11-25T10:39:40","modified_gmt":"2019-11-25T02:39:40","slug":"for-in-%e4%b8%8e-for-of","status":"publish","type":"post","link":"http:\/\/blog.xrhoujie.com\/?p=639","title":{"rendered":"for in \u4e0e for of"},"content":{"rendered":"<p>\u5148\u8bf4\u7ed3\u8bba\uff1a<\/p>\n<ol>\n<li>\u63a8\u8350\u5728\u5faa\u73af\u5bf9\u8c61\u5c5e\u6027\u7684\u65f6\u5019\uff0c\u4f7f\u7528<code>for...in<\/code>,\u5728\u904d\u5386\u6570\u7ec4\u7684\u65f6\u5019\u7684\u65f6\u5019\u4f7f\u7528<code>for...of<\/code>\u3002<\/li>\n<li><code>for...in<\/code>\u5faa\u73af\u51fa\u7684\u662fkey\uff0c<code>for...of<\/code>\u5faa\u73af\u51fa\u7684\u662fvalue<\/li>\n<li>\u6ce8\u610f\uff0c<code>for...of<\/code>\u662fES6\u65b0\u5f15\u5165\u7684\u7279\u6027\u3002\u4fee\u590d\u4e86ES5\u5f15\u5165\u7684<code>for...in<\/code>\u7684\u4e0d\u8db3<\/li>\n<li><code>for...of<\/code>\u4e0d\u80fd\u5faa\u73af\u666e\u901a\u7684\u5bf9\u8c61\uff0c\u9700\u8981\u901a\u8fc7\u548c<code>Object.keys()<\/code>\u642d\u914d\u4f7f\u7528<\/li>\n<\/ol>\n<p>for&#8230;of\u8bed\u53e5\u5728\u53ef\u8fed\u4ee3\u5bf9\u8c61(\u5305\u62ec Array, Map, Set, String, TypedArray\uff0carguments \u5bf9\u8c61\u7b49\u7b49)\u4e0a\u521b\u5efa\u4e00\u4e2a\u8fed\u4ee3\u5faa\u73af\uff0c\u5bf9\u6bcf\u4e2a\u4e0d\u540c\u5c5e\u6027\u7684\u5c5e\u6027\u503c,\u8c03\u7528\u4e00\u4e2a\u81ea\u5b9a\u4e49\u7684\u6709\u6267\u884c\u8bed\u53e5\u7684\u8fed\u4ee3\u6302\u94a9.<\/p>\n<p>\u4e5f\u5c31\u662f\u8bf4\uff0cfor of\u53ea\u53ef\u4ee5\u5faa\u73af\u53ef\u8fed\u4ee3\u5bf9\u8c61\u7684\u53ef\u8fed\u4ee3\u5c5e\u6027\uff0c\u4e0d\u53ef\u8fed\u4ee3\u5c5e\u6027\u5728\u5faa\u73af\u4e2d\u88ab\u5ffd\u7565\u4e86\u3002<br \/>\n\u5e76\u4e14\u7ed9\u4e0e\u4e86\u4e00\u4e2a\u5bf9\u6bd4\u7684\u4f8b\u5b50<\/p>\n<pre class=\"hljs javascript\"><code><span class=\"hljs-built_in\">Object<\/span>.prototype.objCustom = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> () <\/span>{}; \r\n<span class=\"hljs-built_in\">Array<\/span>.prototype.arrCustom = <span class=\"hljs-function\"><span class=\"hljs-keyword\">function<\/span> () <\/span>{};\r\n\r\n<span class=\"hljs-keyword\">let<\/span> iterable = [<span class=\"hljs-number\">3<\/span>, <span class=\"hljs-number\">5<\/span>, <span class=\"hljs-number\">7<\/span>];\r\niterable.foo = <span class=\"hljs-string\">\"hello\"<\/span>;\r\n\r\n<span class=\"hljs-keyword\">for<\/span> (<span class=\"hljs-keyword\">let<\/span> i <span class=\"hljs-keyword\">in<\/span> iterable) {\r\n  <span class=\"hljs-built_in\">console<\/span>.log(i); <span class=\"hljs-comment\">\/\/ logs 0 1 2 foo arrCustom objCustom<\/span>\r\n}\r\n\r\n<span class=\"hljs-keyword\">for<\/span> (<span class=\"hljs-keyword\">let<\/span> i <span class=\"hljs-keyword\">of<\/span> iterable) {\r\n  <span class=\"hljs-built_in\">console<\/span>.log(i); <span class=\"hljs-comment\">\/\/ logs 3, 5, 7<\/span>\r\n}<\/code><\/pre>\n<p>\u6211\u4eec\u53ef\u4ee5\u770b\u5230\uff0c\u5bf9\u4e8earray\u7684\u4e0d\u53ef\u8fed\u4ee3\u5143\u5c5e\u6027objCustom\u3001arrCustom\u548c\u5b9e\u4f8b\u5c5e\u6027foo\uff0c\u5728\u5faa\u73af\u4e2d\u90fd\u88ab\u5ffd\u7565<br \/>\n\u8fd9\u662ffor in\u8fed\u4ee3KEY\uff0cfor of\u8fed\u4ee3value\u4e4b\u5916\u6700\u5927\u7684\u533a\u522b<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u5148\u8bf4\u7ed3\u8bba\uff1a \u63a8\u8350\u5728\u5faa\u73af\u5bf9\u8c61\u5c5e\u6027\u7684\u65f6\u5019\uff0c\u4f7f\u7528for&#8230;in,\u5728\u904d\u5386\u6570\u7ec4\u7684\u65f6\u5019\u7684\u65f6\u5019\u4f7f\u7528for&#8230;of\u3002 fo [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":180,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[10],"tags":[19],"_links":{"self":[{"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=\/wp\/v2\/posts\/639"}],"collection":[{"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=639"}],"version-history":[{"count":1,"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=\/wp\/v2\/posts\/639\/revisions"}],"predecessor-version":[{"id":640,"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=\/wp\/v2\/posts\/639\/revisions\/640"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=\/wp\/v2\/media\/180"}],"wp:attachment":[{"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=639"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=639"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/blog.xrhoujie.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=639"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}