JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//code.jquery.com/jquery-2.1.4.min.js"></script>

JavaScript

function calc(fn) {
  var formula = fn.replace(/[^-()\d/*+.]/g, '');
  try {
    return new Function('return ' + formula)();
  } catch (err) {
    return NaN;
  }
}

var rules = ['12/5*9+9.4*4', '1+2+3+4+5*60', '12/2', '1.50*16.25','alert("test")']

for (var i = 0; i < rules.length; i++) {
  var $div = $('<div/>').text(rules[i] + ' = ' + calc(rules[i]));
  $('body').append($div);
}