Alex Seville Alex Seville - 29 days ago 7
Node.js Question

Global variable vs. require.cache in NodeJS

I know using the

global
variable is discouraged in node, but assuming I need to store some data globally, which is a worse approach:


  1. using global

  2. Using the require cache directly to store an object, i.e.

    require.cache["myGlobalVar"] == {};



I suspect that option 2 is worse because the require cache is intended to be used for modules.

More details:
I thought about using require("myLibrary").myGlobalVar but that would require having myLibrary accessible to all the files calling it, which might not be possible in practice. I'm making a code coverage tool so I can expect the user to install "myLibrary" in their dev/test modules, but not necessarily in their src node_modules directory, to which the instrumented code files would refer.

Answer

Why don't you just create an in memory cache that all of your other code can then reference?

var memoryCache = module.exports = function () {
    var cache = {};
    return {
        get: function (key) { return cache[key]; },
        set: function (key, val) { cache[key] = val; }
    }
}

You can then use the cache from any place by require'ing it.

var cache = require('../cache/memoryCache')();
cache.set('1234', 'value I want to share');
cache.get('1234');  // 'value I want to share'
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