find the smallest distance between two angles

anglediff.js

// from http://stackoverflow.com/a/7869457
// converted to js code
// x and y are the angles in radians

function getDifference(x, y) {
  var a = x-y;
  a = (function(i, j) {return i-Math.floor(i/j)*j})(a+Math.PI, Math.PI*2); // (a+180) % 360; this ensures the correct sign
  a -= Math.PI;
  return a;
}

Very useful util, thank you !