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- <!DOCTYPE html>
- <html lang="en">
- <head>
- <meta charset="UTF-8">
- <meta name="viewport" content="width=device-width, initial-scale=1.0">
- <title>Document</title>
- </head>
- <body>
- <script>
- var arr = [1,2,3,4];
- var obj = {
- name:"Lucy",
- age:10
- }
- var fn1 = function() {
- console.log("你好")
- }
- // 1.typeof
- console.log(typeof 1);//number
- console.log(typeof "1"); //string
- console.log(typeof true); //boolean
- console.log(typeof undefined); //undefined
- console.log(typeof null); //object
- console.log(typeof arr);//object
- console.log(typeof obj);//object
- console.log(typeof fn1);//function
- // 2.instanceof
- console.log(obj instanceof Object);
- console.log(arr instanceof Object);
- console.log(fn1 instanceof Object);
- // 3.Object.prototype.toString.call()
- console.log(Object.prototype.toString.call(1));
- console.log(Object.prototype.toString.call("哈哈"));
- console.log(Object.prototype.toString.call(false));
- console.log(Object.prototype.toString.call(null));
- console.log(Object.prototype.toString.call(undefined));
- console.log(Object.prototype.toString.call(obj));
- console.log(Object.prototype.toString.call(arr));
- console.log(Object.prototype.toString.call(fn1));
-
- // 4.constructor 构造器 无法校验null 和 undefined
- console.log((1).constructor === Number);
- console.log("哈哈".constructor === String);
- console.log(false.constructor === Boolean);
- // console.log(null.constructor === Object);
- // console.log(undefined.constructor === undefined);
- console.log(obj.constructor === Object);
- console.log(arr.constructor === Object);
- console.log(fn1.constructor === Object);
- </script>
- </body>
- </html>
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