let and const keyword
- JavaScript let is a keyword used to declare variables in JavaScript that are block scoped.
- JavaScript const for declaring variables with immutable values, enhancing code stability and readability.
Syntax:
let variable_name = value; // let keyword
const const_name; // const leyword
const x;
Example: Here is the basic example of using let and const keyword.
Javascript
// Using let let x = 10; // Allowed, since x is declared with let x = 20; console.log(x); // Outputs: 20 // Using const const y = 5; y = 8; // Error! Cannot reassign a const variable console.log(y); |
Output:
20
TypeError: Assignment to constant variable.
JS 2015 or ECMAScript 6 (ES6)
JS 2015 (ES6) also known as ECMAScript 6 (ES6), ECMAScript 6 (ES6) is a significant update to JavaScript, introducing arrow functions, classes, template literals, let and const for variable declaration, enhanced object literals, destructuring, and more modern features for better code organization and readability.