How to access object scope inside scroll event?

Question

I have a function foo which is called on window.scroll. I want to access the object variables inside foo, for example i want to print the value of hello from the parent object.

jsfiddle link

 var Object = {
 hello: "hello",

  foo: function(e){
      alert(this.hello); //Prints undefined! I want to get this.hello
  },

  scrollListener: function(){
    var _this = this;
    $(window).scroll(_this.foo);
  },
};

According to JSFiddle, that code is correct when called with Object.foo({}); — Mic1780
– Mic1780, Commented Aug 29, 2014 at 17:03
remove .hello from this and you'll see why. this in your context refers to window — Sterling Archer
– Sterling Archer, Commented Aug 29, 2014 at 17:04
i understand why this is not available. this refers to the scroll event — Anenth
– Anenth, Commented Aug 29, 2014 at 17:10

Mritunjay · Accepted Answer · 2014-08-29 17:09:42Z

2

I think wrapping _this.foo in an anonymous function will do the trick.

Use this in window.scroll

$(window).scroll(function(){
      _this.foo();
});

DEMO

edited Aug 29, 2014 at 17:09

answered Aug 29, 2014 at 17:04

Mritunjay

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Comments

Anenth · Accepted Answer · 2014-08-29 17:23:22Z

0

There are 2 solution

1) use $.proxy to do the trick.

$(window).scroll( $.proxy(_this.foo,this) );

DEMO

2) Return the foo function and then call it.

foo: function(context) {
    var that = context;
    return function(e){ alert(that.hello); }
},

scrollListener: function(){
   var _this = this;
   $(window).scroll(_this.foo(_this));
},

DEMO

edited Aug 29, 2014 at 17:23

answered Aug 29, 2014 at 17:12

Anenth

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