How to declare a global variable from inside a function? [duplicate]

Question

I would like to declare a global variable but on a different page. So all my global variables go on data.js and all the JavaScript functions go on script.js I can do it in JavaScript but how do you do it in jQuery?? When I put my all JavaScript Codes in

$(function() {
    //JavaScript Codes

});

It doesn't work any more.

Here's my code:

http://plnkr.co/edit/u9CLTErGugOZoDTonAl3?p=preview

Nothing changes. Normal JavaScript rules apply. (However, do be aware that "onready" is not executed synchronously.) Anyway, what "doesn't work"? The demo code (a version of which should be included inline in the question) appears to run just fine. — user2864740
– user2864740, Commented Sep 3, 2014 at 23:28
Why do you need global variables? Polluting the global namespace is bad practice and unsafe as anyone at any time can overwrite those variables without you knowing. Using name-spacing and/or patterns such as the Module/Revealing Module pattern might help. Also the use of local storage or similar, if that is required, could also be an option. There is many options aside from polluting the global namespace. It would be good to know why you think you need globals and see if the issue can be solved otherwise before creating a file specifically to host them. — Nope
– Nope, Commented Sep 3, 2014 at 23:37

Stryner · Accepted Answer · 2014-09-03 23:29:52Z

2

All global javascript variables are attached to the window object. You can explicitly bind them to the window object:

$(function() {
    window.test = "Hello";
});
alert(test);

You could also not use the keyword var and they will be implicitly bound to the window object:

$(function() {
    test2 = "World";
});
alert(test2);

Fiddle: http://jsfiddle.net/6tfr2mh6/

answered Sep 3, 2014 at 23:29

Stryner

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2 Comments

RobG Over a year ago

That creates them as properties of the global object, which is subtly different to global variables, e.g. global variables are available before any code executes, whereas global properties are only available once the code that creates them executes (which might be never).

Stryner Over a year ago

Oh, I didn't know that. This answer's incorrect then. I googled it upon your response and a much better answer is here for anyone interested: stackoverflow.com/questions/4862193/javascript-global-variables

masum7 · Accepted Answer · 2014-09-03 23:52:20Z

1

You can simply use javascript variable and use it in another script using jquery. You do not need to declare variable using JQuery.

In data.js

var myValue = "I'm on top of the world!!";

In script.js

$(function() {

  var myFunction = function() {
    $("#demo").html(myValue);
  }

  myFunction();
});

You can see preview here: http://plnkr.co/edit/A9W1rE39DqSLzChX8Qk9?p=preview

answered Sep 3, 2014 at 23:52

masum7

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