JavaScript Random Positive or Negative Number

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;

I've always been a fan of

Math.round(Math.random()) * 2 - 1

as it just sort of makes sense.

• Math.round(Math.random()) will give you 0 or 1

• Multiplying the result by 2 will give you 0 or 2

• And then subtracting 1 gives you -1 or 1.

Intuitive!