Global Variable in app.js accessible in routes?


Question

How do i set a variable in app.js and have it be available in all the routes, atleast in the index.js file located in routes. using the express framework and node.js

1
77
8/14/2013 11:01:35 AM

Accepted Answer

To make a global variable, just declare it without the var keyword. (Generally speaking this isn't best practice, but in some cases it can be useful - just be careful as it will make the variable available everywhere.)

Here's an example from visionmedia/screenshot-app

file app.js:

/**
 * Module dependencies.
 */

var express = require('express')
  , stylus = require('stylus')
  , redis = require('redis')
  , http = require('http');

app = express();

//... require() route files

file routes/main.js

//we can now access 'app' without redeclaring it or passing it in...

/*
 * GET home page.
 */

app.get('/', function(req, res, next){
  res.render('index');
});

//...
57
3/19/2012 7:22:57 AM

It is actually very easy to do this using the "set" and "get" methods available on an express object.

Example as follows, say you have a variable called config with your configuration related stuff that you want to be available in other places:

In app.js:

var config = require('./config');

app.configure(function() {
  ...
  app.set('config', config); 
  ...
}

In routes/index.js

exports.index = function(req, res){
  var config = req.app.get('config');
  // config is now available
  ...
}

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