Question

Let’s say I have a very simple PrototypeJS class that looks like this:

var Foo = Class.create({
  initialize:  function() {
    this.bar = 'bar';
  },

  dostuff:  function() {
    $$('.enabled').each( function(elem) {
      alert(this.bar);  //FAIL
    });
  }
});

This fails because the function being passed to .each() doesn’t have any idea what this refers to.

How can I access the bar attribute of the Class from inside that function?

Answer 1

You can use Prototype’s bind function, which ‘locks [the function’s] execution scope to an object’.

var Foo = Class.create({
  initialize:  function() {
    this.bar = 'bar';
  },

  dostuff:  function() {
    $$('.enabled').each( function(elem) {
      alert(this.bar);
    }.bind(this)); // Set the execution scope to Foo
  }
});