What is this Javascript “require”?

Question

I\'m trying to get Javascript to read/write to a PostgreSQL database. I found this project on github. I was able to get the following sample code to run in node.

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Answer 1

It's used to load modules. Let's use a simple example.

In file circle_object.js:

var Circle = function (radius) {
    this.radius = radius
}
Circle.PI = 3.14

Circle.prototype = {
    area: function () {
        return Circle.PI * this.radius * this.radius;
    }
}

We can use this via require, like:

node> require('circle_object')
{}
node> Circle
{ [Function] PI: 3.14 }
node> var c = new Circle(3)
{ radius: 3 }
node> c.area()

The require() method is used to load and cache JavaScript modules. So, if you want to load a local, relative JavaScript module into a Node.js application, you can simply use the require() method.

Example:

var yourModule = require( "your_module_name" ); //.js file extension is optional