Node.js Basics

Node.js supports JavaScript. So, JavaScript syntax on Node.js is similar to the browser's JavaScript syntax.

Visit JavaScript section to learn about JavaScript syntax in detail.

Primitive Types

Node.js includes following primitive types:

• String
• Number
• Boolean
• Undefined
• Null
• RegExp

Everything else is an object in Node.js.

Loose Typing

JavaScript in Node.js supports loose typing like the browser's JavaScript. Use var keyword to declare a variable of any type.

Object Literal

Object literal syntax is same as browser's JavaScript.

Example: Object

var obj = {
    authorName: 'Ryan Dahl',
    language: 'Node.js'
}

Functions

Functions are first class citizens in Node's JavaScript, similar to the browser's JavaScript. A function can have attributes and properties also. It can be treated like a class in JavaScript.

Example: Function

function Display(x) { 
    console.log(x);
}

Display(100);

Buffer

Node.js includes an additional data type called Buffer (not available in browser's JavaScript). Buffer is mainly used to store binary data, while reading from a file or receiving packets over the network.

process object

Each Node.js script runs in a process. It includes process object to get all the information about the current process of Node.js application.

The following example shows how to get process information in REPL using process object.

> process.execPath
'C:\\Program Files\\nodejs\\node.exe'
> process.pid
1652
> process.cwd()
'C:\\'

Defaults to local

Node's JavaScript is different from browser's JavaScript when it comes to global scope. In the browser's JavaScript, variables declared without var keyword become global. In Node.js, everything becomes local by default.

Access Global Scope

In a browser, global scope is the window object. In Node.js, global object represents the global scope.

To add something in global scope, you need to export it using export or module.export. The same way, import modules/object using require() function to access it from the global scope.

For example, to export an object in Node.js, use exports.name = object.

Example:

exports.log = {
    console: function(msg) {
        console.log(msg);
    },
    file: function(msg) {
        // log to file here
      }
}

Now, you can import log object using require() function and use it anywhere in your Node.js project.

Learn about modules in detail in the next section.