JavaScript file that mimics the functionality of HTML5's placeholder attribute in browsers that don't support it, including Internet Explorer versions older than IE10.

placeholder-support.js

$(function(){

    //code from http://stackoverflow.com/questions/8628522/placeholder-not-working-for-internet-explorer

    var _debug = false;
    var _placeholderSupport = function() {
        var t = document.createElement("input");
        t.type = "text";
        return (typeof t.placeholder !== "undefined");
    }();

    function HandlePlaceholder(oTextbox) {
        if (!_placeholderSupport) {
            var curPlaceholder = oTextbox.getAttribute("placeholder");
            if (curPlaceholder && curPlaceholder.length > 0) {
                Debug("Placeholder found for input box '" + oTextbox.name + "': " + curPlaceholder);
                oTextbox.value = curPlaceholder;
                oTextbox.setAttribute("old_color", oTextbox.style.color);
                oTextbox.style.color = "#c0c0c0";
                oTextbox.onfocus = function() {
                    Debug("input box '" + this.name + "' focus");
                    this.style.color = this.getAttribute("old_color");
                    if (this.value === curPlaceholder)
                        this.value = "";
                };
                oTextbox.onblur = function() {
                    Debug("input box '" + this.name + "' blur");
                    if (this.value === "") {
                        this.style.color = "#c0c0c0";
                        this.value = curPlaceholder;
                    }
                };
            }
            else {
                Debug("input box '" + oTextbox.name + "' does not have placeholder attribute");
            }
        }
        else {
            Debug("browser has native support for placeholder");
        }
    }

    function Debug(msg) {
        if (typeof _debug !== "undefined" && _debug) {
            var oConsole = document.getElementById("Console");
            if (!oConsole) {
                oConsole = document.createElement("div");
                oConsole.id = "Console";
                document.body.appendChild(oConsole);
            }
            oConsole.innerHTML += msg + "<br />";
        }
    }

    // below code added by Aaron Silverman; depends on jQuery being loaded.

    function handlePassword($input) {
        var $password = $input.clone().attr('type','text');
        $input.after($password);
        $input.hide();
        $password.on('focus', function(ev) {
            $password.remove();
            $input.show();
            $input.focus();
        });
        HandlePlaceholder($password.get(0));
    }

    $('input').each(function(i, el) {
        var $input = $(el);
        var type = $input.attr('type');
        if (!type || type === 'text') {
            HandlePlaceholder(el);
        } else if (type === 'password') {
            handlePassword($input);
            $input.on('change', function(ev) {
                if (!$input.val()) {
                    handlePassword($input);
                }
            });
        }
    });

});