JS: Assignment Operators

By Xah Lee. Date: 2022-08-29. Last updated: 2026-09-16.

Assignment operators

var = val

assign val to var, and return val [see let Declaration]

let zz;
console.log((zz = 3) + 1);
// 4

++x

increase x by 1, return the new value.

let x = 1;
let xresult = ++x;

console.log(x);
// 2

console.log(xresult);
// 2

x++

increase x by 1, return the old value.

let x = 1;
let xresult = x++;

console.log(x);
// 2

console.log(xresult);
// 1

--x

decrease x by 1, return the new value.

let x = 1;
let xresult = --x;

console.log(x);
// 0

console.log(xresult);
// 0

x--

decrease x by 1, return the old value.

let x = 1;
let xresult = x--;

console.log(x);
// 0

console.log(xresult);
// 1