errorsk-4nQwBFp0LP8NpyK9WwwoT3BlbkFJyH23SKdFWR1P9Sr63sF8
最编程
2024-08-12 14:57:37
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这里纯粹对象指的是通过 {}或者通过构造函数new出来的对象,不包括数组等对象
因为开发过程中经常要判断一下是否是真正的对象,比如要用到for in等,又老记错,所以在这里记录一下,需要的时候再来看
const obj = {};
1、toString 注意大小写,推荐用此方法
Object.prototype.toString.call(obj) === '[object Object]'
2、constructor
obj.constructor === Object
3、instanceof 需要注意的是数组也是对象,所以 arr instanceof Object 也为true。
obj instanceof Object
4、typeof 注意除了 {} , null 和 [] 也是 'object'
typeof obj === Object
typeof undefined 'undefined'
typeof true 'boolean'
typeof 123 'number'
typeof "abc" 'string'
typeof function() {} 'function'
typeof {} 'object'
typeof null 'object'
typeof [] 'object'
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