Make number Value opposite in JavaScript

Question

I want to know if it is possible to make a number the opposite to what it currently is using JavaScript. ie if a number is 400. Is it possible to make it -400, similar if a number is -400 is it possible to make it 400?

Answer 1

This is not jQuery!

Just multiply it by -1.

num = "400"
console.log(-num);

Answer 2

Core JS,

function opposite(number) {
  return(-number);
}

As the shorter solution from http://www.codewars.com/

Answer 3

In one Line..

 const opposite = number => -number;