Persian to English - Converter [numbers]

HTML

<input type="text"/>
<button type="button">click me</button>
<p></p>

JavaScript

$(document).ready(function(){
	$("button").click(function(){
  	var val = $("input").val();
    var newval = val.toEnDigit();
    $("p").html(newval);
  });
  
  
});

String.prototype.toEnDigit = function() {
    return this.replace(/[\u0660-\u0669]+/g, function(digit) {
        var ret = '';
        for (var i = 0, len = digit.length; i < len; i++) {
            ret += String.fromCharCode(digit.charCodeAt(i) - 1728);
        }
        return ret;
    });
};