phpjs/functions/math/asin.js

php.js offers community built php functions in javascript

function asin(arg) {
  // From: http://phpjs.org/functions
  // +   original by: Onno Marsman
  // *     example 1: asin(0.3);
  // *     returns 1: 0.3046926540153975
  return Math.asin(arg);
}