Find if a NodeJS module is available to require or not

.gitignore

node_modules

module_exist.js

var mod = require('module');

module.exports = function module_exist(name){
  /**
   * This is UGLY but since we're not allowed to require 'native_module'
   * this is the only way to test if a native module (or non-native module) exist.
   */
  try{
    require(name);
  } catch(err){
    if(err.code === 'MODULE_NOT_FOUND'){
      return false;
    }
  }

  return true;
};

package.json

{
  "name": "node-module_exist",
  "description": "Find if a NodeJS module is available to require or not",
  "version": "0.0.1",
  "main": "module_exist.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": {
    "type": "git",
    "url": "git@gist.github.com:3135914.git"
  },
  "homepage": "https://github.com/FGRibreau",
  "author": {
    "name": "Francois-Guillaume Ribreau",
    "url": "http://fgribreau.com.com/"
  },
  "devDependencies": {
    "nodeunit": "~0.7.4"
  },
  "keywords": [
    "core",
    "modules"
  ],
  "license": "MIT"
}

test.js

var exist = require('./');

module.exports.nativeModules = function(t){
  t.expect(3);
  t.equal(exist('fs'), true, "fs module exist");
  t.equal(exist('module'), true, "module module exist");
  t.equal(exist('redis'), false, "redis module doesn't exist");
  t.done();
};

module.exports.notNativeModules = function(t){
  t.expect(2);
  t.equal(exist('nodeunit'), true, "nodeunit module exist");
  t.equal(exist('this_is_gonna_be_legen____wait_for_it____dary'), false, "redis module doesn't exist");
  t.done();
};

Can be also achieved by using require.resolve (which doesn't load the module):

function module_exists( name ) {
  try { return require.resolve( name ) }
  catch( e ) { return false }
}