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  • JavaScript数据类型

    <!DOCTYPE html>
    <html lang="en">
    <head>
        <meta charset="UTF-8">
        <title>Typeof</title>
        <script>
    
            //对象不存在时返回null
            //变量未被赋值是undefined
    
            var test1 = "abcdef";
            var test2 = 123;
            var test3 = true;
            var test4 = {};
            var test5 = [];
            var test6;
            var test7 = {"abcdef": 123};
            var test8 = ["abac", 123];
            function test9(){return "avc"};
            var test10 = null;
    
            console.log(typeof test10)
            //NaN是无法表示的数值,无法自身比较NaN != NaN, NaN与任何东西都不相等
            //判断NaN,任何不是数字的值传给isNaN返回的结果都是true
            var myNum;
            if (isNaN(myNum)){
                myNum = 0;
            }
            alert(myNum);
    
            //Infinity指的是超过数据上限或这下限的值
    
            if (99 == "99"){
                console.log("A number equals a string");
            } else {
                console.log("No way a number equals a strings");
            }
    
        </script>
    </head>
    <body>
    
    </body>
    </html>
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  • 原文地址:https://www.cnblogs.com/themost/p/9313895.html
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