Unicode to Windows1251 From http://stackoverflow.com/questions/7389651/javascript-character-conversion

new_gist_file

function toWindows1252(string, replacement)
{
    var ret = new Array(string.length);    
    var i, ch;

    replacement = typeof replacement === "string" && replacement.length > 0 ? replacement.charCodeAt(0) : 0;

    for (i = 0; i < string.length; i++)
    {
        ch = string.charCodeAt(i);

        if (ch <= 0x7F || (ch >= 0xA0 && ch <= 0xFF))
        {
            ret[i] = ch;
        }
        else
        {
            ret[i] = toWindows1252.table[string[i]];

            if (typeof ret[i] === "undefined") 
            {
                ret[i] = replacement;
            }
        }
    }

    return ret;
}

toWindows1252.table = {
    '\x81': 129, '\x8d': 141, '\x8f': 143, '\x90': 144, 
    '\x9d': 157, '\u0152': 140, '\u0153': 156, '\u0160': 138, 
    '\u0161': 154, '\u0178': 159, '\u017d': 142, '\u017e': 158, 
    '\u0192': 131, '\u02c6': 136, '\u02dc': 152, '\u2013': 150, 
    '\u2014': 151, '\u2018': 145, '\u2019': 146, '\u201a': 130, 
    '\u201c': 147, '\u201d': 148, '\u201e': 132, '\u2020': 134, 
    '\u2021': 135, '\u2022': 149, '\u2026': 133, '\u2030': 137, 
    '\u2039': 139, '\u203a': 155, '\u20ac': 128, '\u2122': 153
};

document.write(toWindows1252('Hello World àèéìòù'));