title: Normalize value from [-x|x] to [-1|1]
body: <p>I want to normalize a value between <code>-x</code> and <code>x</code> to <code>-1</code> and <code>1</code>. </p>
  
  <p>I thought about <code>value / Math.abs(value)</code>, but the problem is if 
  value is 0 that doesn't work. </p>
  
  <p>Is there a possibility without if and else, so with one operation?</p>
  
  <p>Maybe i should add, that the value only can be -x, x, or 0. nothing between.</p>