Calling a class prototype method by a setInterval event

Question

I have a simple javascript class.

One method of this class sets up a timer using setInterval function. The method that I want to call every time the event fires is defined inside the same class.

The question is, how can I pass this method as a parameter to the setInterval function?

One attempt was setInterval('this.showLoading(), 100). But doesn't work. This method access class properties, so I need the 'this' reference.

This is the sample code:

    function LoadingPicture(Id)     {         this.imgArray = null;         this.currentImg = 0;         this.elementId = Id;         this.loadingTimer = null;     }      LoadingPicture.prototype.showLoading = function()     {         if(this.currentImg == imgArray.length)             currentImg = 0;          document.getElementById(this.elementId).src = imgArray[this.currentImg++].src;     }       LoadingPicture.prototype.StartLoading = function()     {         document.getElementById(this.elementId).style.visibility = "visible";         loadingTimer = setInterval("showLoading()", 100);     } 

Answer 1

setInterval can take a function directly, not just a string. https://developer.mozilla.org/en/DOM/window.setInterval

i.e.

loadingTimer = setInterval(showLoading, 100); 

But, for optimal browser compatibility, you should use a closure with an explicit reference:

 var t = this;  loadingTimer = setInterval(function(){t.showLoading();}, 100);