phpjs/functions/bc/bcmul.js

php.js offers community built php functions in javascript

function bcmul(left_operand, right_operand, scale) {
  //  discuss at: http://phpjs.org/functions/bcmul/
  // original by: lmeyrick (https://sourceforge.net/projects/bcmath-js/)
  //  depends on: _phpjs_shared_bc
  //   example 1: bcmul(1, 2);
  //   returns 1: 3
  //        todo: implement these testcases

  var libbcmath = this._phpjs_shared_bc();

  var first, second, result;

  if (typeof scale === 'undefined') {
    scale = libbcmath.scale;
  }
  scale = ((scale < 0) ? 0 : scale);

  // create objects
  first = libbcmath.bc_init_num();
  second = libbcmath.bc_init_num();
  result = libbcmath.bc_init_num();

  first = libbcmath.php_str2num(left_operand.toString());
  second = libbcmath.php_str2num(right_operand.toString());

  result = libbcmath.bc_multiply(first, second, scale);

  if (result.n_scale > scale) {
    result.n_scale = scale;
  }
  return result.toString();
}