phpjs/functions/math/sqrt.js

php.js offers community built php functions in javascript

function sqrt(arg) {
  //  discuss at: http://phpjs.org/functions/sqrt/
  // original by: Onno Marsman
  //   example 1: sqrt(8723321.4);
  //   returns 1: 2953.5269424875746

  return Math.sqrt(arg);
}