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.assert(x === 2);

console.assert(xresult === 2);

x++

increase x by 1, return the old value.

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

console.assert(x === 2);

console.assert(xresult === 1);

--x

decrease x by 1, return the new value.

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

console.assert(x === 0);

console.assert(xresult === 0);

x--

decrease x by 1, return the old value.

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

console.assert(x === 0);

console.assert(xresult === 1);