js deep copy object

When js is dealing with complex data, it may involve the copying of reference type objects or arrays. The following are two methods of copying objects or arrays:

1. Using the method that comes with jquery, the call is simple and convenient

// Shallow copy (only copy the values ​​at the root level of the object)
var newObject = jQuery.extend({}, oldObject);

// deep copy (will copy the entire (including root node and child nodes) object value)
var newObject = jQuery.extend(true, {}, oldObject); 


Second, you can copy layer by layer by js loop, as follows 

　// Shallow copy (only copy the values ​​of the object root level)
　

var old_obj = {a:{b:50}};
function copyBoot(obj){
    var newobj = {};
    for ( var attr in obj) {
        newobj[attr] = obj[attr];
    }
    return newobj;
}
var obj2 = copyBoot(obj);
obj2.a.b = 20;
alert(obj.a.b);

// deep copy (will copy the entire (including root node and child nodes) object value)

var obj = {a:{b:50}};
function copyAll(obj){
    if(typeof obj != 'object'){
        return obj;
    }
    var newobj = {};
    for ( var attr in obj) {
        newobj[attr] = copyAll(obj[attr]);
    }
    return newobj;
}
var obj2 = copyAll(obj);
obj2.a.b = 20;
alert(obj.a.b);