phpjs/functions/math/octdec.js

php.js offers community built php functions in javascript

function octdec(oct_string) {
  //  discuss at: http://phpjs.org/functions/octdec/
  // original by: Philippe Baumann
  //   example 1: octdec('77');
  //   returns 1: 63

  oct_string = (oct_string + '')
    .replace(/[^0-7]/gi, '');
  return parseInt(oct_string, 8);
}