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@@ -0,0 +1,54 @@
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+<!DOCTYPE html>
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+<html lang="en">
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+<head>
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+ <meta charset="UTF-8">
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+ <meta name="viewport" content="width=device-width, initial-scale=1.0">
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+ <title>Document</title>
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+</head>
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+<body>
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+ <!-- 判断数据类型 -->
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+ <script>
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+ // 判断数据类型
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+ let str = "hello";
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+ let num = 100;
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+ let bool = true;
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+ let nul = null;
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+ let unde = undefined;
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+ let obj = {a:1};
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+ let arr = [1,2,3];
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+
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+ // 方法一：typeof 他不能判断 null、Array、Object
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+ // console.log(typeof str);
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+ // console.log(typeof num);
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+ // console.log(typeof bool);
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+ // console.log(typeof nul);
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+ // console.log(typeof unde);
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+ // console.log(typeof obj);
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+ // console.log(typeof arr);
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+
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+ // 方法二：instanceof
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+ // console.log(str instanceof String);
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+ // console.log(num instanceof Number);
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+ // console.log(bool instanceof Boolean);
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+ // // 注意：null、undefined 不能用 instanceof 判断
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+ // // console.log(nul instanceof null);
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+ // // console.log(unde instanceof undefined);
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+ // console.log(obj instanceof Object);
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+ // console.log(arr instanceof Array);
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+
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+ // 方法三：Object.prototype.toString.call() 可以判断任何类型
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+ // console.log(obj.toString());
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+ // console.log(Object.prototype.toString.call(str));
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+ // console.log(Object.prototype.toString.call(num));
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+ // console.log(Object.prototype.toString.call(bool));
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+ // console.log(Object.prototype.toString.call(nul));
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+ // console.log(Object.prototype.toString.call(unde));
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+ // console.log(Object.prototype.toString.call(obj));
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+ // console.log(Object.prototype.toString.call(arr));
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+
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+ // 方法四：Array.isArray() 只能判断 Array 类型
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+ // console.log(Array.isArray(arr));
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+ // console.log(Array.isArray(obj));
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+ </script>
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+</body>
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+</html>
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