How to call this.function within setTimeout in JS?

Question

I have the following JS:

function TrackTime() {

    this.CountBack = function(secs) {
        setTimeout(function(){this.CountBack(secs)}, SetTimeOutPeriod);
    }

}

I have tried this with a closure (seen above) and also about a dozen other ways. I can't seem to get this to work in any browser. The setTimeout function works fine when not being called in a "class" function. Can someone please help me with this?

Answer 1

This happens because of the change in the scope of "this" when the function is executed.

Try that-this trick..

    function TrackTime() {  
        this.CountBack = function(secs) {         
            var that = this;

            setTimeout(function(){that.CountBack(secs)}, SetTimeOutPeriod);     
        };
    }