React 1

ES6 Syntax and Feature Overview

Variable declaration

ES6 introduced the let which allows to a block scope declaration of the varibles unlike var which will declare a variable globally or locally to the entire function regardless of any inner scopes declared (i.e. a variable declared using var will be accessed ant where in the glabal scope or inside the function).

ES6 also introduced the const keyword, which cannot be redeclared or reassigned, but is not immutable, meaning, if you store an object, you may edit this object’s content.

Arrow function syntax

A shorter way of declaring functions, takes the formula of parameters => expression, it can’t be used as method, or constructor, does not have prototype, and using this will refer to the global scope itself.

Template literals

Using the ${variable name} will let you call varibles inside strings, multi line strings also can be written but whitespace must be taken into consideration.

Method definition shorthand

Inside classes there is no need to write function to declare a method.

Key/property shorthand

Calling variables inside an object is enough if you want to tur them to properties.

Classes/constructor functions

class is used to declare a class, constructor is used to set object properties, and extends for inherting (making a subclass of a class)

React

React is a component library based on JS in which JSX is used to write HTML component inside JavaScript synatx and you can also use{} to write expressions inside HTML, JSX also helps preventing injection attacks by escaping any embedded values before rendering them.