Javascript-从子回调中更新父对象

Question

I would like to set a property of a parent object every time a child object runs a callback function.

I have the following code:

function Track(id) {
    this.callback = function(args) {
        this.name = args;
    }

    this.child = new objectName(this.callback, property);
    this.name = this.child.name;
}

I want this.name to be updated every time this.callback is called...Is there any way to do this?

Answer 1

It's a typical scoping issue, this will not reference to parent object when the callback is called.

Try this instead:

function Track(id) {
    var that = this;
    this.callback = function(args) {
        that.name = args;
    }

    this.child = new objectName(this.callback, property);
    this.name = this.child.name;
}

edit: see merlin's comment for a good explanation why this can be a cause for problems. There might also be other possibilities to solve this, ie the usage of bind() , but for that you'll have to pass the parent into the objectName contructor as well.