Below are few code snippets and links that are helpful when you start developing a NodeJS application.


If you haven’t worked with JavaScript in the last few years, these three points should give you enough knowledge to feel comfortable reading the React documentation:

  • We define variables with let and const statements. For the purposes of the React documentation, you can consider them equivalent to var.
  • We use the class keyword to define JavaScript classes. There are two things worth remembering about them. Firstly, unlike with objects, you don’t need to put commas between class method definitions. Secondly, unlike many other languages with classes, in JavaScript the value of this in a method depends on how it is called.
  • We sometimes use => to define “arrow functions”. They’re like regular functions, but shorter. For example, x => x * 2 is roughly equivalent to function(x) { return x * 2; }. Importantly, arrow functions don’t have their own this value so they’re handy when you want to preserve the this value from an outer method definition.

Creating a hello world app

Setting Up Your Editor

Converting a Function to a Class

You can convert a function component like Clock to a class in five steps:

  1. Create an ES6 class, with the same name, that extends React.Component.
  2. Add a single empty method to it called render().
  3. Move the body of the function into the render() method.
  4. Replace props with this.props in the render() body.
  5. Delete the remaining empty function declaration.

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