Import variables from another JavaScript file

Question

Let's say I want to display all seasons of Family Guy as one number. (15) But of course there will be more seasons so I would have to change in every file the 15 to 16 and so on. That for I want to create a variable for the value so I just have to change it once for all files.

external js.script

var seasons = "15"; 
document.getElementById('seasons').innerHTML = seasons;

So now I want to include the variable in my HTML files:

<div id="seasons"></div>

It works but after three variables all other are not displayed.

Is there a better way to create variables in an external file?

What do you mean "but after three variables all other are not displayed"? The number of variables shouldn't change the functionality here. — Mike Cluck
– Mike Cluck, Commented Dec 1, 2016 at 19:00
I am having the same issue, the first three variables will display, but then I get an error: "Cannot set property 'innerHTML' of null" even though it worked for the first three (my variables are identical at this stage). — Harry Cosslett
– Harry Cosslett, Commented Apr 8, 2017 at 4:10

Mike Cluck · Accepted Answer · 2016-12-01 19:05:50Z

2

If you need a group of constants within your application, it's usually a good idea to load them on to a namespace and load that in before any of your other code.

/* app.js */
// Create the namespace
var App = {};

App.Constants = {
  FAMILY_GUY: 15,
  SIMPSONS: 28,
  FUTURAMA: 7
};

/* family-guy.js */
document.getElementById('familyGuy').innerHTML = App.Constants.FAMILY_GUY;

/* simpsons.js */
document.getElementById('simpsons').innerHTML = App.Constants.SIMPSONS;

/* futurama.js */
document.getElementById('futurama').innerHTML = App.Constants.FUTURAMA;

<div id="familyGuy"></div>
<div id="simpsons"></div>
<div id="futurama"></div>

<!-- 
Imagine you're loading your files like this
<script src="app.js"></script>
<script src="family-guy.js"></script>
<script src="simpsons.js"></script>
<script src="futurama.js"></script>
-->

answered Dec 1, 2016 at 19:05

Mike Cluck

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2 Comments

Timo Over a year ago

Thank you! But is there another way than creating lots of little js script files?

Mike Cluck Over a year ago

@Timo You can make as many or as few files as you want. That's all up to you. Theoretically you could write all of this in one file. This shows you how to create a global variable, App, that holds your constants rather than individual variables.

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