The purpose of hypot() isn't to have a pythagoras shortcut, but to overcome overflow issues.

Author: infusion

functions/math/hypot.js

@@ -1,10 +1,18 @@
 function hypot(x, y) {
   //  discuss at: http://phpjs.org/functions/hypot/
   // original by: Onno Marsman
+  // imprived by: Robert Eisele (http://www.xarg.org/)
   //   example 1: hypot(3, 4);
   //   returns 1: 5
   //   example 2: hypot([], 'a');
   //   returns 2: 0
 
-  return Math.sqrt(x * x + y * y) || 0;
+  x = Math.abs(x);
+  y = Math.abs(y);
+
+  var t = Math.min(x, y);
+  x = Math.max(x, y);
+  t = t / x;
+
+  return x * Math.sqrt(1 + t * t);
 }