function strlen (string) {
    // http://kevin.vanzonneveld.net
    // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Sakimori
    // +      input by: Kirk Strobeck
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   bugfixed by: Onno Marsman
    // +    revised by: Brett Zamir
    // %        note 1: May look like overkill, but in order to be truly faithful to handling all Unicode
    // %        note 1: characters and to this function in PHP which does not count the number of bytes
    // %        note 1: but counts the number of characters, something like this is really necessary.
    // *     example 1: strlen('Kevin van Zonneveld');
    // *     returns 1: 19
    // *     example 2: strlen('A\ud87e\udc04Z');
    // *     returns 2: 3
 
    var str = string+'';
    var i = 0, chr = '', lgth = 0;
 
    var getWholeChar = function (str, i) {
        var code = str.charCodeAt(i);
        var next = '', prev = '';
        if (0xD800 <= code && code <= 0xDBFF) { // High surrogate(could change last hex to 0xDB7F to treat high private surrogates as single characters)
            if (str.length <= (i+1))  {
                throw 'High surrogate without following low surrogate';
            }
            next = str.charCodeAt(i+1);
            if (0xDC00 > next || next > 0xDFFF) {
                throw 'High surrogate without following low surrogate';
            }
            return str[i]+str[i+1];
        } else if (0xDC00 <= code && code <= 0xDFFF) { // Low surrogate
            if (i === 0) {
                throw 'Low surrogate without preceding high surrogate';
            }
            prev = str.charCodeAt(i-1);
            if (0xD800 > prev || prev > 0xDBFF) { //(could change last hex to 0xDB7F to treat high private surrogates as single characters)
                throw 'Low surrogate without preceding high surrogate';
            }
            return false; // We can pass over low surrogates now as the second component in a pair which we have already processed
        }
        return str[i];
    };
 
    for (i=0, lgth=0; i < str.length; i++) {
        if ((chr = getWholeChar(str, i)) === false) {
            continue;
        } // Adapt this line at the top of any loop, passing in the whole string and the current iteration and returning a variable to represent the individual character; purpose is to treat the first part of a surrogate pair as the whole character and then ignore the second part
        lgth++;
    }
    return lgth;
}

function str_replace(search, replace, subject) {
    // http://kevin.vanzonneveld.net
    // +   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
    // *     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 f = search, r = replace, s = subject;
    var ra = r instanceof Array, sa = s instanceof Array, f = [].concat(f), r = [].concat(r), i = (s = [].concat(s)).length;
 
    while (j = 0, i--) {
        if (s[i]) {
            while (s[i] = (s[i]+'').split(f[j]).join(ra ? r[j] || "" : r[0]), ++j in f){};
        }
    };
 
    return sa ? s : s[0];
}