Node REPL

Before we get into creating programs and apps with Node.js, let's get a feet wet with the Node.js REPL. Just type node in your terminal. This will create a Node.js environment where we can write and execute JavaScript. You'll see that all that JS knowledge you have learned carries over to Node.js! 💯. Although, some things, specifically browser based API's probably won't work. Go ahead, try an alert('hello world') and see what happens. You'll get an error. Although the Node.js runtime uses JS as it's languge, none of the Browser based globals that you are familiar with actually exist in Node.js or they are pollyfilled to prevent runtime errors.

File Execution

The Node REPL it nice, but you can't build an application with that. We need to be able write our code to a file and tell Node.js to execute that.

Create a file called:index.js

In that file, write some JS. Try out console.log('hello there'). To execute this .js file in the Node.js runtime, we can use the node command with the file name as an argument.

> node index.js