Flip the strings down.

str_flipDown.js

(function () {
    function flip() {
        var result = flipString(document.f.original.value.toLowerCase());
        document.f.flipped.value = result;
    }

    function flipString(aString) {
        var last = aString.length - 1;
        var result = new Array(aString.length)
        for (var i = last; i >= 0; --i) {
            var c = aString.charAt(i)
            var r = flipTable[c]
            result[last - i] = r !== undefined ? r : c
        }
        return result.join('')
    }
    var flipTable = {
        a: '\u0250',
        b: 'q',
        c: '\u0254',
        d: 'p',
        e: '\u01DD',
        f: '\u025F',
        g: '\u0183',
        h: '\u0265',
        i: '\u0131',
        j: '\u027E',
        k: '\u029E',
        l: '\u05DF',
        m: '\u026F',
        n: 'u',
        r: '\u0279',
        t: '\u0287',
        v: '\u028C',
        w: '\u028D',
        y: '\u028E',
        '.': '\u02D9',
        '[': ']',
        '(': ')',
        '{': '}',
        '?': '\u00BF',
        '!': '\u00A1',
        "\'": ',',
        '<': '>',
        '_': '\u203E',
        '"': '\u201E',
        '\\': '\\',
        ';': '\u061B',
        '\u203F': '\u2040',
        '\u2045': '\u2046',
        '\u2234': '\u2235'
    }
    for (var i in flipTable) {
        flipTable[flipTable[i]] = i
    }
})();