JSON方法

  • JSON.parse(JSON.stringfy())可用作一般对象拷贝
  • JSON.stringfy()会破坏函数类型，Date类型
var obj = {
	name:'abc',
	test() {return 1}
}
JSON.stringify(obj) //'{"name":"abc"}'
 
var obj = {
	name:'abc',
	toJSON() {return 1}
}
JSON.stringify(obj) //'1'

polyfill

ES5简单实现

function deepClone(origin, target) {
    var tar = target || {};
    var toStr = Object.prototype.toString;
    var arrType = '[object Array]';
 
    for(var k in origin) {
        if(origin.hasOwnProperty(k)) {
            if(typeof origin[k] === 'object' && origin[k] !== null) {
                tar[k] = toStr.call(origin[k]) === arrType ? [] : {};
                deepClone(origin[k], tar[k]);
            } else {
                tar[k] = origin[k];
            }
        }
    }
    return tar;
}

ES6 使用WeakMap避免循环引用(WeakMap键名只能是 对象)

function deepCloneWithMap(origin, map = new WeakMap()) {
    //null undefined 以及原始值类型直接返回
    if(origin == undefined || typeof origin !== 'object') {
        return origin;
    }
    if(origin instanceof Date) {
        return new Date(origin);
    }
    if(origin instanceof RegExp) {
        return new RegExp(origin);
    }
    //解决循环引用问题
    if (map.get(origin)) {
        return map.get(origin);
    }
 
    const target = new origin.constructor();
    map.set(origin, target);
 
    for(let k in origin) {
        if(origin.hasOwnProperty(k)) {
            target[k] = deepCloneWithMap(origin[k], map);
        }
    }
    return target;
}