數據類型檢測

1 typeof檢測 2 var obg = {}; 3 var ary = []; 4 var reg = /^$/; 5 var fn = function () {}; 6 var num = 1; 7 var bool = true; 8 var nul = null; 9 var undef = undefined; 10 var str = ""; 11 console.log(typeof obg);//"object" 12 console.log(typeof ary);//"object" 13 console.log(typeof num);//"number" 14 console.log(typeof reg);//"object" 15 console.log(typeof fn);//"function" 16 console.log(typeof bool);//"boolean" 17 console.log(typeof nul);//"object" 18 console.log(typeof undef);//"undefined" 19 console.log(typeof str);//"string"*/
typrof不能具體細分是正則、數組、null、對象，因為用typeof檢測的時候結果都是"object"

2、instanceof檢測，只要在實例的原型鏈上檢測出來的結果都是true

1 var num = 1;字面量方式創建 2 console.log( 1 instanceof Number); ->false 3 var num = new Number(1);實例方式創建 4 console.log( num instanceof Number);->true 5 var ary = []; 6 console.log(ary instanceof Array);->true 7 console.log(ary instanceof Object);->true 8 var fn = function () {}; 9 console.log(fn instanceof Function);->true 10 console.log(fn instanceof Object);->true

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1 var num = 1;字面量方式創建 2 console.log( 1 instanceof Number); ->false 3 var num = new Number(1);實例方式創建 4 console.log( num instanceof Number);->true 5 var ary = []; 6 console.log(ary instanceof Array);->true 7 console.log(ary instanceof Object);->true 8 var fn = function () {}; 9 console.log(fn instanceof Function);->true 10 console.log(fn instanceof Object);->true 3、constructor 構造函數可以處理基本數據類型檢測

1 var ary = []; 2 console.log( ary.constructor === Array); 3 var num = 1; 4 console.log(num.constructor === Number) 4、Object.prototype.toString.call最準確最常用的方法

1 var ary = []; 2 var reg = /^$/; 3 var fn = function () {}; 4 var num = 1; 5 var bool = true; 6 console.log(Object.prototype.toString.call(ary));->[object Array] 7 console.log(Object.prototype.toString.call(reg));->[object RegExp] 8 console.log(Object.prototype.toString.call(fn));->[object Function] 9 console.log(Object.prototype.toString.call(num));->[object Number] 10 console.log(Object.prototype.toString.call(bool));->[object Boolean]

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轉載于:https://www.cnblogs.com/wuxianqiang/p/6445122.html

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