function str_replace (search, replace, subject, count) {
    // Replaces all occurrences of search in haystack with replace
    //
    // version: 1102.614
    // discuss at: http://phpjs.org/functions/str_replace    // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Gabriel Paderni
    // +   improved by: Philip Peterson
    // +   improved by: Simon Willison (http://simonwillison.net)
    // +    revised by: Jonas Raoni Soares Silva (http://www.jsfromhell.com)    // +   bugfixed by: Anton Ongson
    // +      input by: Onno Marsman
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +    tweaked by: Onno Marsman
    // +      input by: Brett Zamir (http://brett-zamir.me)    // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   input by: Oleg Eremeev
    // +   improved by: Brett Zamir (http://brett-zamir.me)
    // +   bugfixed by: Oleg Eremeev
    // %          note 1: The count parameter must be passed as a string in order    // %          note 1:  to find a global variable in which the result will be given
    // *     example 1: str_replace(' ', '.', 'Kevin van Zonneveld');
    // *     returns 1: 'Kevin.van.Zonneveld'
    // *     example 2: str_replace(['{name}', 'l'], ['hello', 'm'], '{name}, lars');
    // *     returns 2: 'hemmo, mars'    var i = 0,
        j = 0,
        temp = '',
        repl = '',
        sl = 0,        fl = 0,
        f = [].concat(search),
        r = [].concat(replace),
        s = subject,
        ra = r instanceof Array,        sa = s instanceof Array;
    s = [].concat(s);
    if (count) {
        this.window[count] = 0;
    }
    for (i = 0, sl = s.length; i < sl; i++) {
        if (s[i] === '') {
            continue;
        }        for (j = 0, fl = f.length; j < fl; j++) {
            temp = s[i] + '';
            repl = ra ? (r[j] !== undefined ? r[j] : '') : r[0];
            s[i] = (temp).split(f[j]).join(repl);
            if (count && s[i] !== temp) {                this.window[count] += (temp.length - s[i].length) / f[j].length;
            }
        }
    }
    return sa ? s : s[0];}

    function updateForm()
    {
        var donation = document.donation.amount.value;
        var donation = str_replace(',', '.', donation);
        var coins = donation * 20;
        document.getElementById("coins").innerHTML = coins;

        document.donation.item_name.value = coins + " FGunZ Coins";
        document.donation.item_number.value = coins;
    }