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JavaScript

varlevi
varlevi
8,113 Points
Posted by varlevi
varlevi
8,113 Points

Const, let, and var

I've been working through the JavaScript and the DOM course recently, and noticed that Guil used the keywords let and const to create variables, instead of the var keyword. What's the difference between these three, as Guil seemed to use them interchangeably in place of var. Thanks!

2 Answers

Eric Butler
Eric Butler
33,512 Points

let and const are modern replacements for var as ways to declare a variable in JavaScript. They are used in different contexts: once you define a const, its value can't be changed. If you want to have a change-able variable, use let.

Jan Oberreiter
Jan Oberreiter
78,020 Points
Jan Oberreiter
Jan Oberreiter
78,020 Points

"const" is a signal that the identifier won't be reassigned. "let", is a signal that the variable may be reassigned, such as a counter in a loop, or a value swap in an algorithm. It also signals that the variable will be used only in the block it's defined in, which is not always the entire containing function. "const'" and 'let" is a new feature of ECMA-Script 6 and you shouldn't use "var" anymore unless you revise legacy code.