JS深浅拷贝

// 浅拷贝
var json1 = {
    name: 'aaa',
    age: 25,
    data: {
        a: 1,
        b: 2
    }
};

function copy(parent, child) {
    var child = child || {};
    for(var i in parent) {
        child[i] = parent[i];
    }
    return child;
}

var json2 = copy(json1);
json2.data.a = 3;
console.log(json1.data.a);// json1.data.a受影响也变成3了
console.log(json2.data.a);

// 深拷贝：利用递归
var json1 = {
    name: 'aaa',
    age: 25,
    data: {
        a: 1,
        b: 2
    }
};

function deepCopy(parent, child) {
    var child = child || {};// 并不是直接声明一个新child为空{}，传过来的就用传过来的
    for(var i in parent) {
        if(typeof parent[i] === 'object') {
            child[i] = (parent[i].constructor === Array) ? [] : {};// child.data = {};
            deepCopy(parent[i], child[i]);// {a: 1,b: 2}，传过去的是child.data的空json
        }
        else {
            child[i] = parent[i];// child.data.a ...
        }
    }
    return child;
}

var json2 = deepCopy(json1);
json2.data.a = 3;
console.log(json1.data.a);// json1.data.a不受影响，仍旧是1
console.log(json2.data.a);