How to make a global javascript function and variable?

Question

I have a variable and a function in a file hello.js as below:

I want to call the above function and access the variable from another file, say app.js, (both files in the same folder) var width = 500;

function reset() { //some code }

How should I be doing it.

Thanks.

EDIT:

Actually,

I have the above variable and function inside another function, (I didn't mention earlier, I thought I will take hints and make it work):

Its like this:

var Engine = (function(global) { var width = 500; var canvas = doc.createElement('canvas'), canvas.width = 500; function reset() { //some code })(this);

Now I am trying to access these function and variable, like below:

console.log(Engine.canvas.width); Engine.reset();

It doesn't recognize reset() and canvas.

JS knows nothing about files and folders.

zerkms
– zerkms

2015-03-20 03:37:35 +00:00
Commented Mar 20, 2015 at 3:37 — zerkms
– zerkms, Commented Mar 20, 2015 at 3:37

Jack · Accepted Answer · 2015-03-20 04:12:09Z

Per your edit, you would have to expose the variables by returning/exposing them (or you could create a constructor with methods/properties for an Engine instance...)

var Engine = (function() { var width = 500; // private var canvasEl = document.createElement('canvas'); canvasEl.width = 500; function reset() { // some reset code } return { canvas: canvasEl, reset: reset } })(this); console.log(Engine.canvas.width) // 500

loveNZ · Accepted Answer · 2015-03-20 03:40:55Z

0

you can assign anything to the window object, and then it will be able to be accessed from anywhere.

window.width = 500;

then you can do use window.width to get the value from anywhere.

answered Mar 20, 2015 at 3:40

loveNZ

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4 Comments

nnnnnn Over a year ago

As compared to var width as shown in the question, which also creates a global variable.

loveNZ Over a year ago

yes, it is true, but I think assign to window object make the global variable more explicit, which I think it is good, as you can always inspect the window object to see what are the global values you have.

Felix Kling Over a year ago

You can also inspect globals in the window object if you don't explicitly assign to window. I agree with you though.

jasonscript Over a year ago

If you're going to add variables to the global scope, using names such as width should be strongly reconsidered as it is too generic and too likely to be used by other code

loveNZ · Accepted Answer · 2016-11-20 19:20:38Z

//app.js var Engine = function(global){ var engine = { width: global.width, reset: function(newValue){ something.width = newValue; global.width = newValue; } } return engine;

}

var myEngine = new Engine(window);

console.log(myEngine.width); myEngine.reset('600px');

//secondFile.js //window.width = '500px'

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