phpjs/functions/math/cosh.js

php.js offers community built php functions in javascript

function cosh(arg) {
  // From: http://phpjs.org/functions
  // +   original by: Onno Marsman
  // *     example 1: cosh(-0.18127180117607017);
  // *     returns 1: 1.0164747716114113
  return (Math.exp(arg) + Math.exp(-arg)) / 2;
}