Question

I’m trying to make a chain reaction by executing next function after executing previous one. Code looks like this:

var med = {

    imgLoadTime : 2000,

    easingEffect : 'easeOutQuart',

    scrollEase : 'easeInOutQuad',

    effectDuration : 1000,

    currentPage : '',

    runAnimations : function(){
                        if(this.currentPage == '#slide5'){
                            this.initAssets();
                        }
                    },

    initAssets : function(){
                    $('#asset-1').animate(
                        {left : '50%'}, 
                        { 
                            duration: this.effectDuration, 
                            easing: this.easingEffect, 
                            complete: this.assetTwo 
                        });
                },

    assetTwo : function(){
                    console.log('two');
                    debugger;
                    $('#asset-2').animate(
                        {left : '50%'}, 
                        { 
                            duration: this.effectDuration, 
                            easing: this.easingEffect, 
                            complete: this.assetThree 
                        });
                },

    assetThree : function(){
                    console.log('three');
                    $('#asset-3').animate(
                        {left : '50%'}, 
                        {
                            duration: this.effectDuration, 
                            easing: this.easingEffect, 
                            complete: console.log('weszlo')
                        });
                }

};  

This is how my object looks like. Then I run function runAnimations as a property of object. What is weird that during this chain only assetTwo function executes, but no further (assetThree). Why so?

Answer 1

You can’t do this type of definition:

complete: this.assetTwo 

It will call assetTwo, but it won’t have the right this value. Instead, you need to do this:

           initAssets : function(){
                var self = this;
                $('#asset-1').animate(
                    {left : '50%'}, 
                    { 
                        duration: this.effectDuration, 
                        easing: this.easingEffect, 
                        complete: function() {self.assetTwo()}
                    });
            },

Same for the other complete functions. You need to save the value of this into a local variable and then use it in the complete function to invoke the next method. This will make sure that this is set properly for the next method.