how can I exchange the value of 2 variables without using a third one, in Javascript, thanks

Answer 1

In ES6, you can use array destructuring. Example
let a = 1
let b = 2
[a, b] = [b, a]
console.log(a - b) //outputs 1 (2 - 1)

Answer 2

It is quit simple
var a = 10;
var b = 20;
[a,b]=[b,a]
console.log(a,b);

See this

Answer 3

thanks, for me the best solution is destructuring array