1）instanceof运算符判断类型
function Aaa(){ //父类 this.name = '小明' } let a = new Aaa() let str = new String('asd'); let str2 = 'asdf'; let obj = {name:'小明'}; let arr = []; let bool = new Boolean(false); let bool2 = true; let num = new Number(456); let num2 = 456; console.log(a instanceof Object) // true console.log(a instanceof Aaa) // true console.log(str instanceof String) // true console.log(str instanceof Object) // true console.log(str2 instanceof String) // false console.log(str2 instanceof Object) // false console.log(obj instanceof Object) // true console.log(arr instanceof Array) // true console.log(arr instanceof Object) // true console.log(bool instanceof Boolean) // true console.log(bool instanceof Object) // true console.log(bool2 instanceof Boolean) // false console.log(bool2 instanceof Object) // false console.log(num instanceof Number) // true console.log(num instanceof Object) // true console.log(num2 instanceof Number) // false console.log(num2 instanceof Object) // false 2）利用Object原型上的toString方法判断，最准确
function Aaa(){ //父类 this.name = '小明' } let a = new Aaa() let str = new String('asd'); let str2 = 'asdf'; let obj = {name:'小明'}; let arr = []; let bool = new Boolean(false); let bool2 = true; let num = new Number(456); let num2 = 456; console.log(Object.prototype.toString.call(a)) //'[object Object]' console.log(Object.prototype.toString.call(str)) //'[object String]' console.log(Object.prototype.toString.call(str2)) // '[object String]' console.log(Object.prototype.toString.call(obj))// '[object Object]' console.log(Object.prototype.toString.call(arr)) // '[object Array]' console.log(Object.prototype.toString.call(bool)) // '[object Boolean]' console.log(Object.prototype.toString.call(bool2)) //'[object Boolean]' console.log(Object.prototype.toString.call(num)) //'[object Number]' console.log(Object.prototype.toString.call(num2)) //'[object Number]' console.log(Object.prototype.toString.call(num2) == '[object Number]') //true 版权声明：本文内容由互联网用户自发贡献，该文观点仅代表作者本人。本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌侵权/违法违规的内容， 请联系我们举报，一经查实，本站将立刻删除。
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