javascript – include external .js file in node.js app-ThrowExceptions

Exception or error:

I have an app.js node application. As this file is starting to grow, I would like to move some part of the code in some other files that I would “require” or “include” in the app.js file.

I’m trying things like:

// Declare application
var app = require('express').createServer();

// Declare usefull stuff for DB purposes
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var ObjectId = Schema.ObjectId;

// THE FOLLOWING REQUIRE DOES NOT WORK
require('./models/car.js');

in car.js:

// Define Car model
CarSchema = new Schema({
  brand        : String,
  type : String
});
mongoose.model('Car', CarSchema);

I got the error:

ReferenceError: Schema is not defined

I’m just looking to have the content of car.js loaded (instead of having everything in the same app.js file) Is there a particuliar way to do this in node.js ?

How to solve:

To place an emphasis on what everyone else has been saying var foo in top level does not create a global variable. If you want a global variable then write global.foo. but we all know globals are evil.

If you are someone who uses globals like that in a node.js project I was on I would refactor them away for as there are just so few use cases for this (There are a few exceptions but this isn’t one).

// Declare application
var app = require('express').createServer();

// Declare usefull stuff for DB purposes
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var ObjectId = Schema.ObjectId;

require('./models/car.js').make(Schema, mongoose);

in car.js

function make(Schema, mongoose) {
    // Define Car model
    CarSchema = new Schema({
      brand        : String,
      type : String
    });
    mongoose.model('Car', CarSchema);
}

module.exports.make = make;

###

The correct answer is usually to use require, but in a few cases it’s not possible.

The following code will do the trick, but use it with care:

var fs = require('fs');
var vm = require('vm');
var includeInThisContext = function(path) {
    var code = fs.readFileSync(path);
    vm.runInThisContext(code, path);
}.bind(this);
includeInThisContext(__dirname+"/models/car.js");

###

Short answer:

// lib.js
module.exports.your_function = function () {
  // Something...
};

// app.js
require('./lib.js').your_function();

###

you can put

var mongoose = require('mongoose');
var Schema = mongoose.Schema;

at the top of your car.js file for it to work, or you can do what Raynos said to do.

###

If you just want to test a library from the command line, you could do:

cat somelibrary.js mytestfile.js | node

###

This approach works for me in Node.js, Is there any problem with this one?

File ‘include.js’:

fs = require('fs');

File ‘main.js’:

require('./include.js');

fs.readFile('./file.json', function (err, data) {
    if (err) {
        console.log('ERROR: file.json not found...')
    } else {
        contents = JSON.parse(data)
    };
})

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