深拷贝

// 不考虑拷贝普通类型
function deepCopy(obj,copy){

    var copy = copy || {};
    for(var i in obj){
        if(typeof obj[i] === 'object'){
            copy = obj[i].constructor == Array?[]:{};
            deepCopy(obj[i],copy);
        }else{
            copy[i] = obj[i];
        }
    }

    return copy;
};

// 考虑普通类型
function deepCopy(obj){
    let newObj = null;
    // 普通类型直接返回
    if(!isNormalType(obj)){
        return obj;
    }

    newObj = isNormalType(obj)==='object'?{}:[];

    for (var i in obj) {
        if (!isNormalType(obj[i])) {
            newObj[i] = obj[i];
        } else {
            newObj[i] = deepCopy(obj[i]);
        }
    }
    return newObj;

    function isNormalType(item){
        var type = Object.prototype.toString.call(item);
        if(type=='[object Array]'){
            return 'array';
        }else if(type=='[object Object]'){
            return 'object';
        }else{
            return false;
        }
    }
}


var obj = [];
var newObj = deepCopy(obj);
console.log(Object.prototype.toString.call(obj));