javascript - Error when calling a method in a setInterval

I am having trouble calling methods in a setInterval... Here is a snippet of my code...

var example = function(){


    this.animate = function(){
        console.log("Animate.");
    }

    this.updateTimer = function(){ // This is being called...
        this.timer = setInterval(function(){
            this.animate(); // A "Undefined Is Not A Function" error is being thrown here.
        }, 1);
    }


}

Answer

USE BIND (as @torazaburo said)

maybe best-practice

http://jsfiddle.net/rnrlabs/Lnmex1y7/

var example = function(){

    this.animate = function(){
        console.log("Animate.");
    }    
    this.updateTimer = function() { // This is being called...
        this.timer = setInterval(this.animate.bind(this), 1);
    }
}

OR.. USE A CLOSURE

http://jsfiddle.net/rnrlabs/zk6hdnf2/

var example = function(){

    var self = this; // this creates a closure

    this.animate = function(){
        console.log("Animate.");
    }


    this.updateTimer = function(){ 
        this.timer = setInterval(function(){
            // 'this' here means window element.
            self.animate(); 
        }, 1);
    }

}