urlencode en javascript

urlencode.js

function urlencode( str ) {
 
    // *     ejemplo 1: urlencode('Yeco is Lazy!');
    // *     retorna 1: 'Yeco+is+Lazy%21'
    // *     ejemplo 2: urlencode('http://Yeco.isLazy.net/');
    // *     retorna 2: 'http%3A%2F%2FYeco.isLazy.net%2F'
    // *     ejemplo 3: urlencode('http://www.google.nl/search?q=php.js&ie=utf-8&oe=utf-8&aq=t&rls=com.ubuntu:en-US:unofficial&client=firefox-a');
    // *     retorna 3: 'http%3A%2F%2Fwww.google.nl%2Fsearch%3Fq%3Dphp.js%26ie%3Dutf-8%26oe%3Dutf-8%26aq%3Dt%26rls%3Dcom.ubuntu%3Aen-US%3Aunofficial%26client%3Dfirefox-a'

    var histogram = {}, unicodeStr='', hexEscStr='';
    var ret = (str+'').toString();

    var replacer = function(search, replace, str) {
        var tmp_arr = [];
        tmp_arr = str.split(search);
        return tmp_arr.join(replace);
    };

    // el histograma es identico al que existe en urldecode.
    histogram["'"]   = '%27';
    histogram['(']   = '%28';
    histogram[')']   = '%29';
    histogram['*']   = '%2A';
    histogram['~']   = '%7E';
    histogram['!']   = '%21';
    histogram['%20'] = '+';
    histogram['\u00DC'] = '%DC';
    histogram['\u00FC'] = '%FC';
    histogram['\u00C4'] = '%D4';
    histogram['\u00E4'] = '%E4';
    histogram['\u00D6'] = '%D6';
    histogram['\u00F6'] = '%F6';
    histogram['\u00DF'] = '%DF';
    histogram['\u20AC'] = '%80';
    histogram['\u0081'] = '%81';
    histogram['\u201A'] = '%82';
    histogram['\u0192'] = '%83';
    histogram['\u201E'] = '%84';
    histogram['\u2026'] = '%85';
    histogram['\u2020'] = '%86';
    histogram['\u2021'] = '%87';
    histogram['\u02C6'] = '%88';
    histogram['\u2030'] = '%89';
    histogram['\u0160'] = '%8A';
    histogram['\u2039'] = '%8B';
    histogram['\u0152'] = '%8C';
    histogram['\u008D'] = '%8D';
    histogram['\u017D'] = '%8E';
    histogram['\u008F'] = '%8F';
    histogram['\u0090'] = '%90';
    histogram['\u2018'] = '%91';
    histogram['\u2019'] = '%92';
    histogram['\u201C'] = '%93';
    histogram['\u201D'] = '%94';
    histogram['\u2022'] = '%95';
    histogram['\u2013'] = '%96';
    histogram['\u2014'] = '%97';
    histogram['\u02DC'] = '%98';
    histogram['\u2122'] = '%99';
    histogram['\u0161'] = '%9A';
    histogram['\u203A'] = '%9B';
    histogram['\u0153'] = '%9C';
    histogram['\u009D'] = '%9D';
    histogram['\u017E'] = '%9E';
    histogram['\u0178'] = '%9F';

    // Inicia con encodeURIComponent, que más se asemeja a las funciones de codificacio de PHP
    ret = encodeURIComponent(ret);

    for (unicodeStr in histogram) {
        hexEscStr = histogram[unicodeStr];
        ret = replacer(unicodeStr, hexEscStr, ret); // Custom replace. No regexing
    }

    // Mayusculas para compatibilidad con PHP
    return ret.replace(/(\%([a-z0-9]{2}))/g, function(full, m1, m2) {
        return "%"+m2.toUpperCase();
    });
}