区分数据类型

1.分两类 原始值，引用值，null单独处理
2.区分引用值

function typeFn(target){
    if(target===null) return null;
    let  template={
        '[object Array]':'array',
        '[object Object]':'object',
        '[object Number]':'number-object',
        '[object Boolean]':'boolean-object',
        '[object String]':'string-object',
    }
    if(typeof(target)=='object'){
        return template[Object.prototype.toString.call(target)];
    }else{
        return typeof(target);
    }
}
let arr=new String('12')
console.log(typeFn(arr));//string-object