Why is my JS Loop overwriting previous entries in my object?

Question

Why is my JS Loop overwriting previous entries in my object?

So I have an object, that I'm using in nodejs. It looks as such:

for(var i = 0; i < x.length; i++) {
            var sUser = x[i];
            mUsers[sUser.userid] = CreateUser(sUser);
            ++mUsers.length;
        }

So I'm pulling information from an external source, and it breaks down as an array full of instances of this:

[{ name: 'Michael Lovesllamas Lankford',
 created: 1338420951.11,
 laptop: 'pc',
 laptop_version: null,
 userid: '4fc6aed7eb35c14ad6000057',
 acl: 0,
 fans: 1,
 points: 5,
 avatarid: 34 }]

and so forth.

so that information is passed as x in the above function.

global.mUsers = {length:0}

global.UserBase = {
    userid: -1,
    name: "noidea",
    isSuperUser: false,
    isDJ: false,
    laptop: "pc" };

process.on("registered", OnRegistered);

global.OnRegistered = function(a) {
        //misc code here
        RegisterUsers(a.users);
        //misc code here
}

global.CreateUser = function(a) {
    var b = UserBase;
    b.userid = a.userid;
    b.name = a.name;
    b.laptop = a.laptop;
    if (a.acl > 0) b.isSuperUser = true;
    return b;
};

global.RegisterUsers = function(x) {
        for(var i = 0; i < x.length; i++) {
            var sUser = x[i];
            mUsers[sUser.userid] = sUser;
            ++mUsers.length;
        }

}

Now, I've logged it in the loop, and mUsers[sUser.userid] does indeed = sUser. but when I console.log(mUsers) immediately after the loop, I get this:

{ 
 userid1: { userid: userid3, name: name3, item: item3 },
 userid2: { userid: userid3, name: name3, item: item3 },
 userid3: { userid: userid3, name: name3, item: item3 }
}

And I don't know why it's overwriting. Any ideas?

javascript
node.js
object
loops

Answer 1

The main problem is that you where continuously referencing the same object when you where calling CreateUser, as such it was simply updating and returning a reference which was being kept through out all the calls, this is why when you where printing it, it just printed the last update. You need to create a copy of the object.

global.CreateUser = function(a) {
    var b = Object.create(UserBase); // this will create a copy of it.
    b.userid = a.userid;
    b.name = a.name;
    b.laptop = a.laptop;
    if (a.acl > 0) b.isSuperUser = true;
    return b;
};

now CreateUser is actually creating a copy, when you go through the properties the default ones may not appear right away, but theres still there, they've being simply moved to __proto__ you can still call them.

Answer 2

Try the below it is working for me

var obj = {
            userid1: { userid: "userid1", name: "name3", item: "item3" },
            userid2: { userid: "userid2", name: "name3", item: "item3" },
            userid3: { userid: "userid3", name: "name3", item: "item3" }
        };

var muser = {};

for (var key in obj) {
    muser[key] = obj[key];
}