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javascriptnode.jsrequire

In Node.js, how can I load my modules once and then use them throughout the app?

I want to create one global module file, and then have all my files require that global module file. Inside that file, I would load all the modules once and export a dictionary of loaded modules.

How can I do that?

I actually tried creating this file...and every time I require('global_modules'), all the modules kept reloading. It's O(n).

I want the file to be something like this (but it doesn't work):

//global_modules.js - only load these one time
var modules = {
    account_controller: '/account/controller.js',
    account_middleware: '/account/middleware.js',
    products_controller: '/products/controller.js',
    ...
}
exports.modules = modules;
Solution

  • 1. Using a magic variable (declared without var)

    Use magic global variables, without var.

    Example:

    fs = require("fs");

    instead of

    var fs = require("fs");

    If you don't put var when declaring the variable, the variable will be a magic global one.

    I do not recommend this. Especially, if you are in the strict mode ("use strict") that's not going to work at all.

    2. Using global.yourVariable = ...

    Fields attached to global object become global variables that can be accessed from anywhere in your application.

    So, you can do:

    global.fs = require("fs");

    This is not that bad like 1., but still avoid it when possible.

    For your example:

    Let's say you have two files: server.js (the main file) and the global_modules.js file.

    In server.js you will do this:

    require("./global_modules");

    and in global_modules.js you will have:

    _modules = {
    account_controller: require('/account/controller.js'),
    account_middleware: require('/account/middleware.js'),
    products_controller: require('/products/controller.js'),
    ...
}

    or

    global._modules = {...}

    In server.js you will be able to do:

    _modules.account_controller // returns require('/account/controller.js'),