{"id":5007,"date":"2016-04-27T14:05:09","date_gmt":"2016-04-27T06:05:09","guid":{"rendered":"https:\/\/sdeno.com\/?p=5007"},"modified":"2018-07-30T16:25:13","modified_gmt":"2018-07-30T08:25:13","slug":"javascript%e5%af%b9%e8%b1%a1%e7%9a%84property%e5%b1%9e%e6%80%a7%e8%af%a6%e8%a7%a3","status":"publish","type":"post","link":"https:\/\/sdeno.com\/?p=5007","title":{"rendered":"JavaScript\u5bf9\u8c61\u7684property\u5c5e\u6027\u8be6\u89e3"},"content":{"rendered":"<p style=\"color: #000000;\">JavaScript\u4e2d\u5bf9\u8c61\u7684property\u6709\u4e09\u4e2a\u5c5e\u6027\uff1a<br \/>\n1.writable\u3002\u8be5property\u662f\u5426\u53ef\u5199\u3002<br \/>\n2.enumerable\u3002\u5f53\u4f7f\u7528for\/in\u8bed\u53e5\u65f6\uff0c\u8be5property\u662f\u5426\u4f1a\u88ab\u679a\u4e3e\u3002<br \/>\n3.configurable\u3002\u8be5property\u7684\u5c5e\u6027\u662f\u5426\u53ef\u4ee5\u4fee\u6539\uff0cproperty\u662f\u5426\u53ef\u4ee5\u5220\u9664\u3002<\/p>\n<p style=\"color: #000000;\">\u5728ECMAScript 3\u6807\u51c6\u4e2d\uff0c\u4e0a\u9762\u4e09\u4e2a\u5c5e\u6027\u7684\u503c\u5747\u4e3atrue\u4e14\u4e0d\u53ef\u6539\uff1a\u65b0\u5efa\u5bf9\u8c61\u7684property\u662f\u53ef\u5199\u7684\u3001\u53ef\u88ab\u679a\u4e3e\u7684\u3001\u53ef\u5220\u9664\u7684\uff1b\u800c\u5728ECMAScript 5\u6807\u51c6\u4e2d\uff0c\u53ef\u901a\u8fc7property\u7684\u63cf\u8ff0\u5bf9\u8c61(property descriptor)\u6765\u5bf9\u8fd9\u4e9b\u5c5e\u6027\u8fdb\u884c\u914d\u7f6e\u548c\u4fee\u6539\u3002<\/p>\n<pre>var obj = {};\r\n\r\nObject.defineProperty(obj, 'name', {\r\n    configurable: true, \/\/\u5141\u8bb8\u5220\u9664name\u5c5e\u6027\u540d\uff0cdelete obj.name\r\n    writable: true, \/\/\u5141\u8bb8\u4fee\u6539\r\n    enumerable: true, \/\/\u5141\u8bb8\u679a\u4e3e fon...in\r\n    value: '\u5f20\u4e09'\r\n});\r\n\r\n\r\nObject.defineProperty(obj, 'age', {\r\n    configurable: false, \/\/\u4e0d\u5141\u8bb8\u5220\u9664\r\n    writable: false, \/\/\u4e0d\u5141\u8bb8\u4fee\u6539\r\n    enumerable: false, \/\/\u4e0d\u5141\u8bb8\u679a\u4e3e\r\n    value:18\r\n});\r\n\r\n\/\/ {name: \"\u5f20\u4e09\", age: 18}\r\n\r\n\r\n--------------------------\r\n\u6216\u8005\r\n--------------------------\r\nvar obj = {};\r\nvar xx;\r\n\r\n\r\nObject.defineProperty(obj, 'age', {\r\n    configurable: true, \r\n    enumerable: true, \r\n    get : function(){\r\n        return xx  \/\/\u8fd9\u91cc\u4e3aage\u5c5e\u6027\u8d4b\u503c\r\n    },\r\n    set:function (v) {\r\n        xx=v;   \r\n    },\r\n});\r\n\r\nobj.age=29\r\n\r\n\r\nconsole.log(JSON.stringify(obj));\r\nconsole.log(xx);  \/\/ 29\r\n\u5148\u6267\u884cset\u51fd\u6570\u5728\u6267\u884cget\u51fd\u6570<\/pre>\n<p>&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p style=\"color: #000000;\">\u5982\u679c\u5c06property\u7684\u503c\u4fe1\u606f\u4e5f\u4f5c\u4e3aproperty\u7684\u5c5e\u6027\u6765\u770b\u7684\u8bdd\uff0c\u5bf9\u8c61\u4e2d\u7684property\u62e5\u6709\u56db\u4e2a\u5c5e\u6027\uff1avalue\u3001writable\u3001enumerable\u548cconfigurable\u3002<\/p>\n<p style=\"color: #000000;\">\u5bf9\u4e8e\u7528getter\u548csetter\u65b9\u6cd5\u6765\u5b9a\u4e49\u7684property\uff0c\u7531\u4e8e\u5176\u6ca1\u6709writable\u5c5e\u6027(property\u662f\u5426\u53ef\u5199\u53d6\u51b3\u4e8esetter\u65b9\u6cd5\u662f\u5426\u5b58\u5728)\uff0c\u56e0\u6b64\u8fd9\u79cdproperty\u4e5f\u6709\u56db\u4e2a\u5c5e\u6027\uff1aget\u3001set\u3001enumerable\u548cconfigurable \u2014 get\u548cset\u5c5e\u6027\u7684\u503c\u4e3afunction\u3002<\/p>\n<p style=\"color: #000000;\"><strong>\u83b7\u53d6\u5bf9\u8c61property\u7684\u5c5e\u6027<\/strong><\/p>\n<p style=\"color: #000000;\">ECMAScript 5\u6807\u51c6\u4e2d\uff0c\u53ef\u4ee5\u901a\u8fc7Object.getOwnPropertyDescriptor()\u6765\u83b7\u53d6\u5bf9\u8c61\u81ea\u8eab\u67d0\u4e2aproperty\u7684\u5c5e\u6027\u4fe1\u606f\uff1a<\/p>\n<div class=\"codetitle\" style=\"color: #000000;\"><a id=\"copybut70000\" class=\"copybut\"><\/a><span style=\"text-decoration: underline;\">\u590d\u5236\u4ee3\u7801<\/span>\u4ee3\u7801\u5982\u4e0b:<\/div>\n<div id=\"code70000\" class=\"codebody\" style=\"color: #000000;\">var o = {x:1};<br \/>\nvar a = Object.create(o);<br \/>\na.y = 3;<br \/>\nconsole.log(Object.getOwnPropertyDescriptor(a, &#8220;y&#8221;));\/\/Object {configurable=true, enumerable=true, writable=true, value=3}<br \/>\nconsole.log(Object.getOwnPropertyDescriptor(a, &#8220;x&#8221;));\/\/undefined<\/div>\n<p><br style=\"color: #000000;\" \/><span style=\"color: #000000;\">\u53ef\u4ee5\u770b\u5230\uff0c\u5982\u679cproperty\u4e0d\u5b58\u5728\u6216\u8005property\u7ee7\u627f\u81ea\u539f\u578b\u5bf9\u8c61\uff0c\u5219\u8fd4\u56deundefined\u3002<\/span><\/p>\n<p style=\"color: #000000;\"><strong>\u8bbe\u7f6e\u5bf9\u8c61property\u7684\u5c5e\u6027<\/strong><\/p>\n<p style=\"color: #000000;\">ECMAScript 5\u6807\u51c6\u4e2d\uff0c\u53ef\u4ee5\u901a\u8fc7Object.defineProperty()\u6765\u8bbe\u7f6e\u5bf9\u8c61\u81ea\u8eab\u67d0\u4e2aproperty\u7684\u5c5e\u6027\uff1a<\/p>\n<div class=\"codetitle\" style=\"color: #000000;\"><a id=\"copybut61714\" class=\"copybut\"><\/a><span style=\"text-decoration: underline;\">\u590d\u5236\u4ee3\u7801<\/span>\u4ee3\u7801\u5982\u4e0b:<\/div>\n<div id=\"code61714\" class=\"codebody\" style=\"color: #000000;\">Object.defineProperty(a, &#8220;y&#8221;, {<br \/>\nvalue:3,<br \/>\nwritable:true,<br \/>\nenumerable:false,<br \/>\nconfiguration:true<br \/>\n});<br \/>\nconsole.log(a.propertyIsEnumerable(&#8220;y&#8221;));\/\/false<\/div>\n<p><br style=\"color: #000000;\" \/><span style=\"color: #000000;\">\u5982\u679c\u8bbe\u7f6e\u7684property\u662f\u4ece\u539f\u578b\u5bf9\u8c61\u4e2d\u7ee7\u627f\u800c\u6765\u7684\uff0c\u90a3\u4e48JavaScript\u5c06\u5728\u5bf9\u8c61\u81ea\u8eab\u4e2d\u521b\u5efa\u4e00\u4e2a\u540c\u540d\u7684property\uff0c\u8fd9\u4e0e\u8d4b\u503c\u64cd\u4f5c\u7684\u76f8\u5173\u884c\u4e3a\u4e00\u81f4\uff1a<\/span><\/p>\n<div class=\"codetitle\" style=\"color: #000000;\"><a id=\"copybut39688\" class=\"copybut\"><\/a><span style=\"text-decoration: underline;\">\u590d\u5236\u4ee3\u7801<\/span>\u4ee3\u7801\u5982\u4e0b:<\/div>\n<div id=\"code39688\" class=\"codebody\" style=\"color: #000000;\">Object.defineProperty(a, &#8220;x&#8221;, {<br \/>\nvalue:1,<br \/>\nwritable:true,<br \/>\nenumerable:false,<br \/>\nconfiguration:true<br \/>\n});<br \/>\nconsole.log(a.propertyIsEnumerable(&#8220;x&#8221;));\/\/false<br \/>\nconsole.log(o.propertyIsEnumerable(&#8220;x&#8221;));\/\/true<\/div>\n<p><br style=\"color: #000000;\" \/><span style=\"color: #000000;\">\u9664\u4e86\u4fee\u6539property\u7684\u5c5e\u6027\uff0c\u8fd8\u53ef\u4ee5\u5c06property\u6539\u4e3a\u7528getter\u6216setter\u8bbf\u95ee\uff1a<\/span><\/p>\n<div class=\"codetitle\" style=\"color: #000000;\"><a id=\"copybut79209\" class=\"copybut\"><\/a><span style=\"text-decoration: underline;\">\u590d\u5236\u4ee3\u7801<\/span>\u4ee3\u7801\u5982\u4e0b:<\/div>\n<div id=\"code79209\" class=\"codebody\" style=\"color: #000000;\">Object.defineProperty(a, &#8220;y&#8221;, {<br \/>\nget:function(){return 42;}<br \/>\n});<br \/>\nconsole.log(a.y);\/\/42<\/div>\n<p><br style=\"color: #000000;\" \/><span style=\"color: #000000;\">\u5728\u4f7f\u7528Object.defineProperty()\u65f6\uff0cproperty\u63cf\u8ff0\u5bf9\u8c61\u4e2d\u7684\u5c5e\u6027\u503c\u53ef\u4ee5\u90e8\u5206\u5ffd\u7565\uff0c\u5f53\u5c5e\u6027\u503c\u6709\u6240\u5ffd\u7565\u65f6\uff0cJavaScript\u4e2d\u7684\u5904\u7406\u89c4\u5219\u5982\u4e0b\uff1a<\/span><\/p>\n<p style=\"color: #000000;\">\u5982\u679cproperty\u662f\u65b0\u5efa\u7684\uff0c\u5219\u6240\u6709\u5ffd\u7565\u7684\u5c5e\u6027\u503c\u5747\u4e3afalse\u6216undefined\u3002<br \/>\n\u5982\u679cproperty\u5df2\u5b58\u5728\uff0c\u5219\u6240\u6709\u5ffd\u7565\u7684\u5c5e\u6027\u503c\u7ef4\u6301\u539f\u6837\u4e0d\u53d8\u3002<\/p>\n<p style=\"color: #000000;\"><strong>\u6279\u91cf\u8bbe\u7f6e\u5bf9\u8c61property\u7684\u5c5e\u6027<\/strong><\/p>\n<p style=\"color: #000000;\">\u5982\u679c\u9700\u8981\u4e00\u6b21\u6027\u8bbe\u7f6e\u591a\u4e2aproperty\u7684\u5c5e\u6027\uff0c\u53ef\u4ee5\u4f7f\u7528Object.defineProperties()\u8bed\u53e5\u3002\u8be5\u8bed\u53e5\u5c06\u8fd4\u56de\u4fee\u6539\u540e\u7684\u5bf9\u8c61\u3002<\/p>\n<div class=\"codetitle\" style=\"color: #000000;\"><a id=\"copybut60646\" class=\"copybut\"><\/a><span style=\"text-decoration: underline;\">\u590d\u5236\u4ee3\u7801<\/span>\u4ee3\u7801\u5982\u4e0b:<\/div>\n<div id=\"code60646\" class=\"codebody\" style=\"color: #000000;\">Object.defineProperties(a, {<br \/>\n&#8220;y&#8221;:{value:79, writable:true, enumerable:true, configurable:true},<br \/>\n&#8220;z&#8221;:{value:99, writable:true, enumerable:true, configurable:true}<br \/>\n});<br \/>\nconsole.log(a);\/\/Object {y=79, z=99}<\/div>\n<p><br style=\"color: #000000;\" \/><strong style=\"color: #000000;\">property\u5c5e\u6027\u8bbe\u7f6e\u89c4\u5219<\/strong><\/p>\n<p style=\"color: #000000;\">\u5f53\u5bf9property\u5c5e\u6027\u8fdb\u884c\u4fee\u6539\u65f6\uff0c\u5fc5\u987b\u9075\u5faa\u4ee5\u4e0b\u89c4\u5219\u3002\u5982\u679c\u8fdd\u53cd\u89c4\u5219\uff0cJavaScript\u5c06\u62a5TypeError\u9519\u8bef\uff1a<\/p>\n<p style=\"color: #000000;\">\u5982\u679c\u5bf9\u8c61\u4e0d\u662fextensible\u7684\uff0c\u5219\u53ea\u80fd\u4fee\u6539\u5df2\u6709property\u7684\u5c5e\u6027\uff0c\u65e0\u6cd5\u6dfb\u52a0\u65b0\u7684property\u3002<br \/>\n\u5982\u679cproperty\u7684configurable\u5c5e\u6027\u4e3afalse\uff0c\u5219\u65e0\u6cd5\u4fee\u6539configurable\u548cenumerable\u5c5e\u6027\u7684\u503c\uff0c\u5bf9\u4e8ewritable\u5c5e\u6027\uff0c\u53ef\u4ee5\u5c06\u5176\u4ecetrue\u6539\u4e3afalse\uff0c\u4f46\u65e0\u6cd5\u5c06\u5176\u4ecefalse\u6539\u4e3atrue\u3002\u5982\u679cproperty\u7531getter\u548csetter\u5b9a\u4e49\uff0c\u5219getter\u548csetter\u65b9\u6cd5\u65e0\u6cd5\u88ab\u4fee\u6539\u3002<br \/>\n\u5982\u679cproperty\u7684configurable\u5c5e\u6027\u548cwritable\u5c5e\u6027\u5747\u4e3afalse\uff0c\u5219property\u503c\u4e0d\u53ef\u6539\u3002\u5982\u679cproperty\u7684writable\u5c5e\u6027\u4e3afalse\uff0c\u4f46\u5176configurable\u5c5e\u6027\u4e3atrue\uff0c\u5219property\u503c\u4f9d\u7136\u53ef\u4ee5\u4fee\u6539\u3002<\/p>\n<p><audio style=\"display: none;\" controls=\"controls\"><\/audio><\/p>\n<p><audio style=\"display: none;\" controls=\"controls\"><\/audio><\/p>\n<p><audio style=\"display: none;\" controls=\"controls\"><\/audio><\/p>\n<p><audio style=\"display: none;\" controls=\"controls\"><\/audio><\/p>\n<p><audio style=\"display: none;\" controls=\"controls\"><\/audio><\/p>\n","protected":false},"excerpt":{"rendered":"<p>JavaScript\u4e2d\u5bf9\u8c61\u7684property\u6709\u4e09\u4e2a\u5c5e\u6027\uff1a 1.writable\u3002\u8be5property\u662f\u5426\u53ef\u5199\u3002  [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[11],"tags":[],"class_list":["post-5007","post","type-post","status-publish","format-standard","hentry","category-11"],"_links":{"self":[{"href":"https:\/\/sdeno.com\/index.php?rest_route=\/wp\/v2\/posts\/5007","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/sdeno.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/sdeno.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/sdeno.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/sdeno.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=5007"}],"version-history":[{"count":0,"href":"https:\/\/sdeno.com\/index.php?rest_route=\/wp\/v2\/posts\/5007\/revisions"}],"wp:attachment":[{"href":"https:\/\/sdeno.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=5007"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/sdeno.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=5007"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/sdeno.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=5007"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}