Formula from String to Int

by Matthew Webb

HTML

<input id="txtbox1" type="text" name="txtbox1" value="5">
<br />
<input id="txtbox2" type="text" name="txtbox2" value="10">
<br />
<button>Click me</button>
<br />
    <p>Answer:</p>
<div id="result"></div>

JavaScript

/**
*      Stack Overflow Answer  
*      Question: http://stackoverflow.com/questions/29485980/how-to-calculate-formula-from-string-to-int/
*/

$(document).on('click', 'button', function () {

    var repl1 = '(GP1/(GP1 + GP2)) * 100%';

    var repl2 = repl1.replace(/GP1/gi, parseInt($('#txtbox1').val(), 10));
    var repl3 = repl2.replace(/GP2/gi, parseInt($('#txtbox2').val(), 10));
    var repl4 = repl3.replace(/%/gi, "");

    $('#result').html(repl4);

});