{"id":2723,"date":"2023-11-14T14:26:31","date_gmt":"2023-11-14T06:26:31","guid":{"rendered":""},"modified":"2023-11-14T14:26:31","modified_gmt":"2023-11-14T06:26:31","slug":"JavaScript typeof","status":"publish","type":"post","link":"https:\/\/bianchenghao6.com\/2723.html","title":{"rendered":"JavaScript typeof"},"content":{"rendered":"<div class=\"titlebox\">\n<h1>JavaScript typeof<\/h1>\n<\/div>\n<div class=\"desc\">\n  JavaScript<br \/>\n <strong> typeof <\/strong>\u8fd0\u7b97\u7b26\u7528\u4e8e\u8fd4\u56de\u4e00\u4e2a\u5b57\u7b26\u4e32\uff0c\u8be5\u5b57\u7b26\u4e32\u4ee3\u8868\u7ed9\u5b9a\u503c\u7684JavaScript\u7c7b\u578b\u3002\u5b83\u4ee5\u5b57\u7b26\u4e32\u5f62\u5f0f\u8fd4\u56de\u64cd\u4f5c\u6570\u7684\u6570\u636e\u7c7b\u578b\u3002\u64cd\u4f5c\u6570\u53ef\u4ee5\u662f\u6587\u5b57\u6216\u6570\u636e\u7ed3\u6784\uff0c\u4f8b\u5982\u51fd\u6570\uff0c\u5bf9\u8c61\u6216\u53d8\u91cf\u3002\n<\/div>\n<h3 class=\" h3\">\u8bed\u6cd5<\/h3>\n<div class=\"desc\">\n  \u4f7f\u7528typeof\u6709\u4ee5\u4e0b\u4e24\u79cd\u65b9\u6cd5\u8fd0\u7b97\u7b26\u3002\n<\/div>\n<div class=\"codebox codeshow\">\n<pre class=\"pure-highlightjs\"><code class=\"null\"><span> typeof operand<br> or<br> typeof (operand)<br> <\/span><\/code><\/pre>\n<\/div>\n<h3 class=\" h3\">\u503c<\/h3>\n<div class=\"desc\">\n <strong>\u64cd\u4f5c\u6570\uff1a<\/strong>\uff1a\u5b83\u662f\u8868\u793a\u8981\u8fd4\u56de\u5176\u7c7b\u578b\u7684\u5bf9\u8c61\u6216\u57fa\u5143\u7684\u8868\u8fbe\u5f0f\u3002\n<\/div>\n<div class=\"desc\">\n <strong> typeof <\/strong>\u8fd0\u7b97\u7b26\u7684\u53ef\u80fd\u8fd4\u56de\u503c\u5217\u8868\u5982\u4e0b\uff1a\n<\/div>\n<table>\n<tbody>\n<tr>\n<td>\u64cd\u4f5c\u6570\u7684\u7c7b\u578b<\/td>\n<td>\u7ed3\u679c<\/td>\n<\/tr>\n<tr>\n<td> <strong>object<\/strong> <\/td>\n<td>\"\u5bf9\u8c61\" <\/td>\n<\/tr>\n<tr>\n<td> <strong>number<\/strong> <\/td>\n<td>\"\u6570\u5b57\" <\/td>\n<\/tr>\n<tr>\n<td> <strong>string<\/strong> <\/td>\n<td>\"\u5b57\u7b26\u4e32\" <\/td>\n<\/tr>\n<tr>\n<td> <strong>boolean<\/strong> <\/td>\n<td>\"\u5e03\u5c14\u503c\" <\/td>\n<\/tr>\n<tr>\n<td> <strong>function<\/strong> <\/td>\n<td>\"\u529f\u80fd\" <\/td>\n<\/tr>\n<tr>\n<td> <strong>undefined<\/strong> <\/td>\n<td>\"\u672a\u5b9a\u4e49\" <\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<div class=\"desc\">\n  \u8ba9\u6211\u4eec\u901a\u8fc7\u4e00\u4e9b\u793a\u4f8b\u6765\u4e86\u89e3\u6b64\u8fd0\u7b97\u7b26\u3002\n<\/div>\n<h3 class=\" h3\"> Example1 <\/h3>\n<div class=\"desc\">\n  \u5728\u6b64\u793a\u4f8b\u4e2d\uff0c\u64cd\u4f5c\u6570\u662f\u6570\u5b57\u7c7b\u578b\u3002<br \/>\n <strong> typeof <\/strong>\u8fd0\u7b97\u7b26\u5c06\u6253\u5370<br \/>\n <strong>\"\u6570\u5b57\" <\/strong>\u4f5c\u4e3a\u64cd\u4f5c\u6570\u7684\u7c7b\u578b\uff0c\u65e0\u8bba\u64cd\u4f5c\u6570\u662f\u8d1f\u6574\u6570\uff0c\u6d6e\u70b9\u6570\uff0c\u65e0\u7a77\u5927\uff0cNaN\uff0c\u96f6\u8fd8\u662f\u4efb\u4f55\u6574\u6570\u3002\n<\/div>\n<div class=\"codebox codeshow\">\n<pre class=\"pure-highlightjs\"><code class=\"null\"><span> &lt;html&gt;<br> &lt;head&gt;<br> &lt;script&gt;<br> document.<span class=\"mediumblue\">write<\/span>(typeof (45) + \"&lt;br&gt;\"); \/\/ results: \"number\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof (-90) + \"&lt;br&gt;\"); \/\/ results: \"number\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof (0) + \"&lt;br&gt;\"); \/\/ results: \"number\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof (22.6) + \"&lt;br&gt;\"); \/\/ results: \"number\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof (Infinity) + \"&lt;br&gt;\"); \/\/ results: \"number\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof (NaN)); \/\/ results: \"number\". Although NaN is \"Not-A-Number\"<br> &lt;\/script&gt;<br> &lt;\/head&gt;<br> &lt;body&gt;<br> &lt;\/body&gt;<br> &lt;\/html&gt;<br> <\/span><\/code><\/pre>\n<\/div>\n<div class=\"desc\">\n <strong>\u8f93\u51fa<\/strong>\n<\/div>\n<div class=\"result\">\n <script>\n                    document.write(typeof(45) + \"<br \/>\"); \/\/ results: \"number\"\n                    document.write(typeof(-90) + \"<br \/>\"); \/\/ results: \"number\"\n                    document.write(typeof(0) + \"<br \/>\"); \/\/ results: \"number\"\n                    document.write(typeof(22.6) + \"<br \/>\"); \/\/ results: \"number\"\n                    document.write(typeof(Infinity) + \"<br \/>\"); \/\/ results: \"number\"\n                    document.write(typeof(NaN)); \/\/ results: \"number\". Although NaN is \"Not-A-Number\"\n                    <\/script>\n<\/div>\n<h3 class=\" h3\"> Example2 <\/h3>\n<div class=\"desc\">\n  \u5728\u6b64\u793a\u4f8b\u4e2d\uff0c\u64cd\u4f5c\u6570\u4e3a\u5b57\u7b26\u4e32\u7c7b\u578b\u3002<br \/>\n <strong> typeof <\/strong>\u8fd0\u7b97\u7b26\u5c06\u6253\u5370<br \/>\n <strong>\"\u5b57\u7b26\u4e32\" <\/strong>\u4f5c\u4e3a\u64cd\u4f5c\u6570\u7684\u7c7b\u578b\uff0c\u65e0\u8bba\u64cd\u4f5c\u6570\u662f\u7a7a\u5b57\u7b26\u4e32\uff0c\u5b57\u7b26\u96c6\u5408\u8fd8\u662f\u7528\u5f15\u53f7\u5f15\u8d77\u6765\u7684\u6570\u5b57\u3002\n<\/div>\n<div class=\"codebox codeshow\">\n<pre class=\"pure-highlightjs\"><code class=\"null\"><span> &lt;html&gt;<br> &lt;head&gt;<br> &lt;script&gt;<br> document.<span class=\"mediumblue\">write<\/span>(typeof (\"\") + \"&lt;br&gt;\"); \/\/ results: \"string\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof (\"bianchenghao6.com\") + \"&lt;br&gt;\"); \/\/ results: \"string\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof (\"20\") + \"&lt;br&gt;\"); \/\/ results: \"string\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof (typeof 1) + \"&lt;br&gt;\"); \/\/ results: \"string\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof String(12)); \/\/ wrapping in String function will results: \"string\"<br> &lt;\/script&gt;<br> &lt;\/head&gt;<br> &lt;body&gt;<br> &lt;\/body&gt;<br> &lt;\/html&gt;<br> <\/span><\/code><\/pre>\n<\/div>\n<div class=\"desc\">\n <strong>\u8f93\u51fa<\/strong>\n<\/div>\n<div class=\"result\">\n <script>\n                    document.write(typeof(\"\") + \"<br \/>\"); \/\/ results: \"string\"\n                    document.write(typeof(\"bianchenghao6.com\") + \"<br \/>\"); \/\/ results: \"string\"\n                    document.write(typeof(\"20\") + \"<br \/>\"); \/\/ results: \"string\"\n                    document.write(typeof(typeof 1) + \"<br \/>\"); \/\/ results: \"string\"\n                    document.write(typeof String(12)); \/\/ wrapping in String function will results: \"string\"\n                    <\/script>\n<\/div>\n<h3 class=\" h3\"> Example3 <\/h3>\n<div class=\"desc\">\n  \u5728\u6b64\u793a\u4f8b\u4e2d\uff0c\u64cd\u4f5c\u6570\u4e3a\u5e03\u5c14\u7c7b\u578b\u3002\u5982\u679c\u64cd\u4f5c\u6570\u4e3a<br \/>\n <strong> true <\/strong>\u6216<br \/>\n <strong> false &lt;\uff0c<strong> typeof <\/strong>\u8fd0\u7b97\u7b26\u5c06\u6253\u5370<strong>\" boolean\" <\/strong>\u4f5c\u4e3a\u64cd\u4f5c\u6570\u7684\u7c7b\u578b\u3002<\/strong>\u3002\n<\/div>\n<div class=\"codebox codeshow\">\n<pre class=\"pure-highlightjs\"><code class=\"null\"><span> &lt;html&gt;<br> &lt;head&gt;<br> &lt;script&gt;<br> document.<span class=\"mediumblue\">write<\/span>(typeof (true) + \"&lt;br&gt;\"); \/\/ results: \"boolean\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof (false) + \"&lt;br&gt;\"); \/\/ results: \"boolean\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof Boolean(20) + \"&lt;br&gt;\"); \/\/ wrapping in Boolean function will results: \"boolean\"<br> &lt;\/script&gt;<br> &lt;\/head&gt;<br> &lt;body&gt;<br> &lt;\/body&gt;<br> &lt;\/html&gt;<br> <\/span><\/code><\/pre>\n<\/div>\n<div class=\"desc\">\n <strong>\u8f93\u51fa<\/strong>\n<\/div>\n<div class=\"result\">\n <script>\n                    document.write(typeof(true) + \"<br \/>\"); \/\/ results: \"boolean\"\n                    document.write(typeof(false) + \"<br \/>\"); \/\/ results: \"boolean\"\n                    document.write(typeof Boolean(20) + \"<br \/>\"); \/\/ wrapping in Boolean function will results: \"boolean\"\n                    <\/script>\n<\/div>\n<h3 class=\" h3\"> Example4 <\/h3>\n<div class=\"desc\">\n  \u5728\u6b64\u793a\u4f8b\u4e2d\uff0c\u64cd\u4f5c\u6570\u662f\u672a\u5b9a\u4e49\u7684\u7c7b\u578b\u3002<br \/>\n <strong> typeof <\/strong>\u8fd0\u7b97\u7b26\u5c06\u6253\u5370<br \/>\n <strong>\"\u672a\u5b9a\u4e49\" <\/strong>\u4f5c\u4e3a\u64cd\u4f5c\u6570\u7684\u7c7b\u578b\u3002\u5728\u8fd9\u91cc\uff0c<br \/>\n <strong>\u7a7a<\/strong>\u7684\u7c7b\u578b\u4e3a<br \/>\n <strong>\u672a\u5b9a\u4e49<\/strong>\uff0c\u8fd9\u662f\u56e0\u4e3a\u5b83\u88ab\u5199\u4e3a<br \/>\n <strong>\u7a7a<\/strong>\u800c\u4e0d\u662f<br \/>\n <strong>\u7a7a<\/strong>\u3002\u5982\u679c\u6211\u4eec\u5c06\u5176\u5199\u4e3a<br \/>\n <strong> null <\/strong>\uff0c\u5219\u5176\u7c7b\u578b\u5c06\u4e3a<br \/>\n <strong> object\u3002<\/strong>\n<\/div>\n<div class=\"codebox codeshow\">\n<pre class=\"pure-highlightjs\"><code class=\"null\"><span> &lt;html&gt;<br> &lt;head&gt;<br> &lt;script&gt;<br> document.<span class=\"mediumblue\">write<\/span>(typeof Null + \"&lt;br&gt;\"); \/\/ results: \"undefined\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof undefined + \"&lt;br&gt;\"); \/\/ results: \"undefined\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof a + \"&lt;br&gt;\"); \/\/ results: \"undefined\"<br> &lt;\/script&gt;<br> &lt;\/head&gt;<br> &lt;body&gt;<br> &lt;\/body&gt;<br> &lt;\/html&gt;<br> <\/span><\/code><\/pre>\n<\/div>\n<div class=\"desc\">\n <strong>\u8f93\u51fa<\/strong>\n<\/div>\n<div class=\"result\">\n <script>\n                    document.write(typeof Null + \"<br \/>\"); \/\/ results: \"undefined\"\n                    document.write(typeof undefined + \"<br \/>\"); \/\/ results: \"undefined\"\n                    document.write(typeof a + \"<br \/>\"); \/\/ results: \"undefined\"\n                    <\/script>\n<\/div>\n<h3 class=\" h3\"> Example5 <\/h3>\n<div class=\"desc\">\n  \u5728\u6b64\u793a\u4f8b\u4e2d\uff0c\u64cd\u4f5c\u6570\u4e3a<br \/>\n <strong> Object <\/strong>\u548c<br \/>\n <strong> Function <\/strong>\u7c7b\u578b\u3002<br \/>\n <strong> typeof <\/strong>\u8fd0\u7b97\u7b26\u5c06\u6839\u636e\u64cd\u4f5c\u6570\u7684\u7c7b\u578b\u6253\u5370<br \/>\n <strong>\"\u5bf9\u8c61\" <\/strong>\u548c<br \/>\n <strong>\"\u529f\u80fd\" <\/strong>\u3002\n<\/div>\n<div class=\"codebox codeshow\">\n<pre class=\"pure-highlightjs\"><code class=\"null\"><span> &lt;html&gt;<br> &lt;head&gt;<br> &lt;script&gt;<br> document.<span class=\"mediumblue\">write<\/span>(typeof null + \"&lt;br&gt;\"); \/\/ results: \"object\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof [1, 2, 'hello'] + \"&lt;br&gt;\"); \/\/ results: \"object\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof {a: 'hello'} + \"&lt;br&gt;\"); \/\/ results: \"object\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof [1, 2, 3, 4] + \"&lt;br&gt;\"); \/\/ results: \"object\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof function(){} + \"&lt;br&gt;\"); \/\/ results: \"function\"<br> document.<span class=\"mediumblue\">write<\/span>(typeof class hello{} + \"&lt;br&gt;\"); \/\/ results: \"function\"<br> &lt;\/script&gt;<br> &lt;\/head&gt;<br> &lt;body&gt;<br> &lt;\/body&gt;<br> &lt;\/html&gt;<br> <\/span><\/code><\/pre>\n<\/div>\n<div class=\"desc\">\n <strong>\u8f93\u51fa<\/strong>\n<\/div>\n<div class=\"result\">\n <script>\n                    document.write(typeof null + \"<br \/>\"); \/\/ results: \"object\"\n                    document.write(typeof [1, 2, 'hello'] + \"<br \/>\"); \/\/ results: \"object\"\n                    document.write(typeof { a: 'hello' } + \"<br \/>\"); \/\/ results: \"object\"\n                    document.write(typeof [1, 2, 3, 4] + \"<br \/>\"); \/\/ results: \"object\"\n                    document.write(typeof\n                        function() {} + \"<br \/>\"); \/\/ results: \"function\"\n                    document.write(typeof class hello {} + \"<br \/>\"); \/\/ results: \"function\"\n                    <\/script>\n<\/div>\n","protected":false},"excerpt":{"rendered":"JavaScript typeofzh-cn","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[179],"tags":[],"class_list":["post-2723","post","type-post","status-publish","format-standard","hentry","category-javascript-jc"],"_links":{"self":[{"href":"https:\/\/bianchenghao6.com\/wp-json\/wp\/v2\/posts\/2723"}],"collection":[{"href":"https:\/\/bianchenghao6.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/bianchenghao6.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/bianchenghao6.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/bianchenghao6.com\/wp-json\/wp\/v2\/comments?post=2723"}],"version-history":[{"count":0,"href":"https:\/\/bianchenghao6.com\/wp-json\/wp\/v2\/posts\/2723\/revisions"}],"wp:attachment":[{"href":"https:\/\/bianchenghao6.com\/wp-json\/wp\/v2\/media?parent=2723"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/bianchenghao6.com\/wp-json\/wp\/v2\/categories?post=2723"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/bianchenghao6.com\/wp-json\/wp\/v2\/tags?post=2723"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}