js对象深拷贝

由于引用类型（数组、对象）是按地址传递，直接拷贝是浅拷贝，即修改拷贝后的变量，原变量也会改变。有时需要深拷贝一个对象，这时就需要遍历彻底复制，使原对象和拷贝对象完全脱离关系。

代码：

    function deepCloneObj(obj){
        var i;
        var o = Array.isArray(obj) ? [] : {};
        for(i in obj){
            if(obj.hasOwnProperty(i)){
                o[i] = typeof obj[i] === "Object"? deepCloneObj(obj[i]) : obj[i];
            }
        }
        return o;
    }

实现细节：假定传入的是一个引用类型，首先判定传入的是数组还是对象，根据判定结果，确定o是初始化为空数组还是空对象。之后遍历传入引用类型的自有属性，并判定属性是否为对象，如果是的话做递归，否则直接复制给o。

数组实例：

    var arr1 = ["sfsag","akghak","['fafa','gaag','rwet']",125];
    console.log(arr1);//["sfsag", "akghak", "['fafa','gaag','rwet']", 125]
    var arr2 = deepCloneObj(arr1);
    arr1.push("newstr");
    console.log(arr1);//["sfsag", "akghak", "['fafa','gaag','rwet']", 125, "newstr"]
    console.log(arr2);//["sfsag", "akghak", "['fafa','gaag','rwet']", 125]

对象实例：

    var obj1 = {sgsh:{sfwg:'ssgsg'},asga:['aff','ghh','wegwer',12],segg:1};
    console.log(obj1);//Object {sgsh: Object, asga: Array[4], segg: 1}
    var obj2 = deepCloneObj(obj1);
    obj1['newstr'] = ['fsg','gsr'];
    console.log(obj1);//Object {sgsh: Object, asga: Array[4], segg: 1, newstr: Array[2]}
    console.log(obj2);//Object {sgsh: Object, asga: Array[4], segg: 1}