jQuery global variable best practice & options?

Question

Currently I am working on a legacy web page that uses a ton of javascript, jquery, microsoft client javascript, and other libraries. The bottom line - I cannot rewrite the entire page from scratch as the business cannot justify it. So... it is what it is. Anyway, I need to pollute (I really tried not too) the global namespace with a variable. There are the three options I was thinking -

1. Just store/retrieve it using a normal javascript declaration - var x = 0;

2. Utilize jQuery to store/retrieve the value in a DOM tag - $("body").data("x", 0);

3. Utilize a hidden form field, and set/retrieve the value with jQuery - $("whatever").data("x", 0);

What does everyone think? Is there a better way? I looked at the existing pile of code and I do not believe the variable can be scoped in a function.

Answer 1

You can create a namespace inside the jQuery object, like so:

$.mynamespace = { 
    myVar : "something", 
    myVar2 : "somethingElse" 
}; 

or:

$.mynamespace = {};
$.mynamespace.myVar = "something";
$.mynamespace.myVar2 = "somethingElse";

Bear in mind, any plugin method named 'mynamespace' will be overwritten so be sure to use a sensible name.

Answer 2

you can create a hash in the global scope and use it as a namespace

MyNamepace={}

MyNamespace.newvar = 'value'

MyNamespace.newvar => 'value'

Answer 3

just sharing my practice with you :

I would make a global object/var in the required js file with a sensible prefix, as in if I am working on a page where this object will be a text box then i would name is

g_TxtMyValue = 'value';    // g_ specifies it to be a global variable, it is one
                           // of the many conventions used

If you have more than one golbal variables you can also have a namespace such as

my_txt = {};  // for a real site i would use a prefix relative to the project
              //  name instead of my

my_txt.testValueOne = 'Value one';
my_txt.testValueOne = 'Value two';

These variables will be available to you throughout the website, after they have been initialized.

Hope this helps

Answer 4

For me the best way to handle this situation is to define an object in the window object:

window.my_config =
{
    my_var1 : 1,
    my_var1 : 2,
    my_var1 : 3
};

This would keep your scope neat and clean. And whenever you would access the global using window.my_config anyone looking at the code would know that a global is being accessed.