let

let – Declares one or more block scope variables, and optionally sets a value to them.

let mixed variable, …

Name	Description	Type	Default	Optional
variable, …	One or more variable values to be set.	mixed		No

Version	Description
ES 6	Introduced.

'use strict';

function doit () {
	let x = 'y'; // Sets "y" an the value for the variable named x.
	console.log(x);
}
doit();

'use strict';

function doit () {
	let a = 'b', x = 'y';
	console.log(a);
	console.log(x);
}
doit();

JavaScript