Can I put a jquery handler in a constructor?

I'm seeing if I can make some object oriented javascript and I have the following code.

When I went to move my jquery event handler into the constructor I became confused because now I have two this variables...

Am I approaching this incorrectly or is there a way to make it work?

function Dropdown(ddlname) {
    this.Value = 0;
    this.Selected = false;
    this.DDL = ddlname;
    this.Limited = false;
    this.SelectLast = function () {
        $(this.DDL + ' option:last').attr('selected', 'selected');
    }
    $(ddlname).change(function () {
        var v = $(this).val(); // <== ? 
        if (typeo开发者_运维百科f v == 'number') {
            this.Value = v; // <== ?
            this.Selected = true; // <== ? 
        }
    });
    return true;
};

You need to assign "this" from the context of your constructor to a local variable to be able to reference it from within your jquery event handler.

function Dropdown(ddlname) {
    this.Value = 0;
    this.Selected = false;
    this.DDL = ddlname;
    this.Limited = false;
    var hold = this;
    this.SelectLast = function () {
        $(hold.DDL + ' option:last').attr('selected', 'selected');
    }
    $(ddlname).change(function () {
        var v = $(this).val(); // <== ? 
        if (typeof v == 'number') {
            hold.Value = v; // <== ?
            hold.Selected = true; // <== ? 
        }
    });
    return true;
};

One trick i learnt from Marcelo Ruiz of DataJS team from microsoft is as follows:

function Dropdown(ddlname) 
{    
    var that = this;
    //rest of your code. now there is no confusion of this since you have that :) 
};

Not sure if this would help you. but just a trick i learned.

Yes you may, but you will need to call the class in the document ready function. I'm pretty sure it's bad practice.

You should consider passing the $ to the constructor or making a jQuery extension.