Need help reaching a variable in JavaScript

Question

Can someone please help me understand the scoop of JavaScript variables, and how to reach them?

Imagine the following...

// Namespace declaration
var p = {};

p.result = {

    searchForm: $('#search-form'),
    searchAction: this.searchForm.attr('action'),

    anotherSection: {
        hello: 'Hello ',
        world: this.hello + 'world!'
    }

}

This won't work, and it gives the error saying this.searchForm is undefined. The same error appears in anotherSection as well (ofc).

How can I declare a variable in terms of another variable inside the same namespace?

Christian C. Salvadó · Accepted Answer · 2009-12-27 15:34:42Z

3

The this keyword is bound to the function-context, you can't use it in object literals like that.

You could, make functions as "getters":

var p = {};
p.result = {
  searchForm: $('#search-form'),
  getSearchAction: function () {
    return this.searchForm.attr('action');
  },
  anotherSection: {
    hello: 'Hello ',
    getWorld: function () {
      return this.hello + 'world!';
    }
  }
};

answered Dec 27, 2009 at 15:34

Christian C. Salvadó

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2 Comments

Mickel Over a year ago

+1 for the edit and code example. I think this looks like a good solution :)

Etan Over a year ago

You could optimize it using this.getWorld = this.hello + 'world!'; return this.getWorld so that it only concatenates the string the first time it gets called.

SLaks · Accepted Answer · 2009-12-27 15:38:03Z

3

There is no way to refer to an object literal as you're building it.

You need to write the following:

p.result = {
    searchForm: $('#search-form'),
    anotherSection: {
        hello: 'Hello '
    }
}

p.result.searchAction = p.result.searchForm.attr('action');
p.result.anotherSection.world = p.result.anotherSection.hello + 'world!';

answered Dec 27, 2009 at 15:38

SLaks

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1 Comment

Mickel Over a year ago

+1 thanks, but I'll go for the solution provided by CMS this time.

Quentin · Accepted Answer · 2009-12-27 15:46:18Z

1

You can't access the properties of an object inside its own literal — they don't exist yet.

answered Dec 27, 2009 at 15:46

Quentin

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Comments

Josh Yeager · Accepted Answer · 2009-12-27 15:35:04Z

0

this is an object, so when you use this.searchForm, you are accessing a property of the this object. You just want to access a variable, so you can just use searchForm.

answered Dec 27, 2009 at 15:35

Josh Yeager

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