思路

1 ).根据 typeof() 的返回值将数据分为2种情况

a.返回值为 'string' 'number' 'boolean' 'undefined' 'function' (直接返回 typeof() 的返回值)

b.返回值为'object'

2 ).再将 typeof() 返回值为 'object' 的数据分为2种情况

a.null (直接返回自身)

b.包装类 对象 数组 (再进行细分)

var a = new Number(1);
function type(target) {var ret = typeof(target);console.log(ret)var template = {//包装类、对象、数组"[object Number]" : "number - object","[object String]" : "string - object","[object Boolean]" : "boolean - object","[object Object]" : "object","[object Array]" : "array"}//找出 nullif(target === null){return null;}if(ret == "object"){var str = Object.prototype.toString.call(target);return template[str];}else{//原始值 和 functionreturn ret;}
}
console.log(type(a))
//number - object
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