How to share data between different modules in requirejs, javascript

Question

I want to share some data between different modules by creating one module, called for instance dataService, put a variable into it, and then insert this module in other modules as a dependency. Here is the code (that doesn't work):

define('dataService', function () {
    var quotes = [];
    return {
    quotesArray: quotes,
        };
});

require(['dataService'], function (dataService) {
     dataService.quotesArray {1, 2, 3};  // setting the quotes variable
});

define('otherModule', ['dataService'], function (dataService) {
     var x = dataService.quotesArray; // x = empty Array, why?
});

Here is the workaround:

define('dataService', function () {
    var quotes = [];
    var getQuotes = function () {       
        return quotes;
    };
    var setQuotes = function (newQuotes) {
        quotes = newQuotes;
    };
    return {
        getQuotes: getQuotes,
    };
});

require(['dataService'], function (dataService) {
    var x = dataService.getQuotes();  // now I can get/set the quotes variable
    dataService.setQuotes();
});

I'm just wondering if it is a proper way to make some data be accessible in different modules?

And why first option doesn't work?

possible duplicate of Using RequireJS, how do I pass in global objects or singletons around? — Steve P
– Steve P, Commented Aug 26, 2013 at 18:31
The first piece works as expected, as this fiddle shows, jsbin.com/ifeyefo/1 . There must be something wrong with your setup. Is this really the code you use, or a simplified example. — Andreas Köberle
– Andreas Köberle, Commented Aug 26, 2013 at 18:40
@Andreas Köberle, sorry, can't open the fiddle. It's approximately the code I'm using. — Aleksei Chepovoi
– Aleksei Chepovoi, Commented Aug 26, 2013 at 18:44
As I say, your example code works fine. Most of the time a required module is undefined, there is a circular reference between the modules. So does the first module requires also the second module in your real code. — Andreas Köberle
– Andreas Köberle, Commented Aug 26, 2013 at 18:49
@Andreas Köberle, sorry for missleading you, I made a mistake. Please, reread the question. I can query dataService.quotesArray, but if I set it in one module, and then query dataService.quotesArray in another module, I get empty array, seems like I haven't set quotes var in a first module — Aleksei Chepovoi
– Aleksei Chepovoi, Commented Aug 26, 2013 at 18:57

Kim T · Accepted Answer · 2013-10-23 00:37:58Z

7

To make this work you need to create an instance of both, so one overwrites the properties of the other:

define('Quotes', function (Module) {
    return {
        quotesArray: ['a', 'b', 'c']
    };
});

define('Service', ['Quotes'], function (quotes) {
    console.log(1, quotes.quotesArray); // ["a", "b", "c"]
    quotes.quotesArray = [1, 2, 3];
});

require(['Service', 'Quotes'], function(service, quotes) {
    console.log(2, quotes.quotesArray); // [1, 2, 3]
});

Here's a working fiddle: http://jsfiddle.net/kmturley/aHgMJ/

answered Oct 23, 2013 at 0:37

Kim T

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2 Comments

kitimenpolku Over a year ago

Are the dependencies load async without any order but executed in the order - service - quotes ?

Kim T Over a year ago

The order would be: Quotes module is defined, Service module is defined, Service module loads Quotes module and overwrites values, Sevice and Quotes modules are loaded and the values are logged out

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