JavaScript Random Positive or Negative Number

Question

I need to create a random -1 or 1 to multiply an already existing number by. Issue is my current random function generates a -1, 0, or 1. What is the most efficient way of doing this?

Answer 1

Don't use your existing function - just call Math.random(). If < 0.5 then -1, else 1:

var plusOrMinus = Math.random() < 0.5 ? -1 : 1;

The Math.random() method returns a floating-point number that's greater than or equal to 0 and less than 1.