All About Variables

How to work with information in JavaScript

Field notes while going through the JavaScript Roadmap

Photo by Luca Bravo on Unsplash

Variable Declarations in JavaScript

• A variable is a “named container” for a value
• To declare a variable in JavaScript, use the let , const or var keyword
• Here’s an example of a variable “message” initialised with the value of string “Hello”

let message;

message = "Hello";

// or

let message = "Hello";

• The string is now saved into memory
• let allows us to change the value that is stored in the variable as many times as we want
• Previously, in older scripts, var was used instead of let (which was introduced in ECMAScript6)— they are similar, but not the same. var is now considered “old-school”
• const is another type of variable like let , however, the value of the variable cannot be changed — hence the shortened name for “constant”
• Variables can store all sorts of data types — such as numbers, strings, booleans, arrays and objects
• JavaScript is a “dynamically typed language” which means that you don’t need to specify what data type a variable will contain before assigning a value