base64 encode email addresses in PHP, and replace with decoded addresses client-side in JavaScript

gistfile1.aw

/*
* I don't like this sort of thing, but I have a client who needs it. 
* What I did for them was to put the email address on the page encoded in base64,
* and use client-side script to decode it.
*/

// server-side...

/**
* return HTML for a base64-encoded email link
* @param string $emailAddress the email address to encode
* @param string $text HTML-clean text to show for the link
* @param boolean $keepText TRUE to keep the text shown, FALSE (default) to replace with email address
* @return string
*/
function getEncodedEmail($emailAddress, $text, $keepText = FALSE) {
    $encoded = base64_encode($emailAddress);
    $classes = $keepText ? 'encoded-hidden keep-text' : 'encoded-hidden';
    return "<span class='$classes' data-enc-email=\"$encoded\">$text</span>";
}


// client-side...

<script>
/**
* find spans with encoded email data, and replace contents with email links
*/
function decodeEmails() {
    var elements, element, i, len, a, text, email, dataName = "data-enc-email";

    function getSelected() {
        // use select query if available
        if (document.querySelectorAll)
            return document.querySelectorAll("span[" + dataName + "]");

        // no select query so go old school
        var found = [];
        elements = document.getElementsByTagName("SPAN");

        // assume IE, so use IE-best loop style
        for (i = elements.length; i--; ) {
            if (simplebase.hasAttribute(elements[i], dataName)) {
                found.push(elements[i]);
            }
        }
        return found;
    }

    elements = getSelected();
    for (i = 0, len = elements.length; i < len; ++i) {
        element = elements[i];
        email = simplebase.decodeBase64_UTF8(element.getAttribute(dataName));

        if (element.className.indexOf("keep-text") != -1)
            text = element.textContent || element.innerText;
        else
            text = email;

        a = document.createElement("A");
        a.href = "mailto:" + email;
        a.appendChild(document.createTextNode(text));
        element.innerHTML = "";
        element.appendChild(a);
        element.className = element.className.replace("encoded-hidden", "");
    }
}

/**
* decode a base64 encoded UTF-8 string
* ref http://ecmanaut.blogspot.com/2006/07/encoding-decoding-utf8-in-javascript.html
* decodeBase64 here: http://phpjs.org/functions/base64_decode:357
* @param {String} data the base64 encoded UTF-8 string
* @return {String}
*/
decodeBase64_UTF8: function(data) {
    return decodeURIComponent(escape(decodeBase64(data)));
}
</script>