Show/hide Hidden Text

manifest.json

{
    "name": "Show/Hide Hidden Text",
    "version": "1",
    "manifest_version": 2,
    "description": "Shows and hides all text hidden in hide tags.",
    "content_scripts": [
        {"matches" : ["http://lifein19x19.com/*",
                      "http://www.lifein19x19.com/*"],
         "js": ["showhide.js"]
        }
    ]
}

showhide.js

// Create a link that shows or hides all hidden comments on an
// lifein19x19.com page. It is designed to work in IE8 or higher, and
// use capability testing to be unobtrusive in older browsers.

// Add a link to the header, to the left of "Previous topic"
function addLink() {
    var headerTarget = document.querySelectorAll('.nav')[2];

    // create a show/hide link and add event listener
    var showHideLink = document.createElement('a');
    showHideLink.setAttribute('href', 'about:blank');
    showHideLink.id = 'showHide';

    if (showHideLink.addEventListener) {
        showHideLink.addEventListener('click', showhide, false);
    } else {
        showHideLink.attachEvent('click', showhide);
    }

    // insert show/hide link in the page
    showHideLink.appendChild(document.createTextNode('Show hidden text'));
    headerTarget.insertBefore(showHideLink,
                              headerTarget.getElementsByTagName('a')[0]);

    // insert a '|' as a vertical divider
    var bar = document.createTextNode(' | ');
    headerTarget.insertBefore(bar,
                              headerTarget.getElementsByTagName('a')[1]);

    trackStatus();
}

function trackStatus () {
    var buttons = localShowHideButtons();
    if (buttons.length && buttons[0].addEventListener) {
        for (var i = 0, ilen = buttons.length; i < ilen; i++) {
            buttons[i].onclick = null;
            buttons[i].addEventListener('click', toggleVisibility, false);
        }
    } else {
        for (var i = 0, ilen = buttons.length; i < ilen; i++) {
            buttons[i].onclick = toggleVisibility;
        }
    }
}

// Return true if any hidden comments have been shown
function visible () {
    var buttons = localShowHideButtons();
    for (var i = 0, ilen = buttons.length; i < ilen; i++) {
        if (buttonTarget(buttons[i]).style.display !== 'none') {
            return true;
        }
    }
    return false;
}

// Update the text of the show/hide control depending on which action
// it will perform.
function checkStatus () {
    var showHide = document.getElementById('showHide');

    if (!visible()) {
        var newText = 'Show hidden text';
    } else {
        newText = 'Hide private comments';
    }

    if (showHide.textContent) {
        showHide.textContent = newText;
    } else if (showHide.innerText) {
        showHide.innerText = newText;
    }
}

function show (button) {
    buttonTarget(button).style.display = '';
    button.textContent = '';
    button.value = 'Hide';
}

function hide (button) {
    buttonTarget(button).style.display = 'none';
    button.textContent = '';
    button.value = 'Show';
}

function toggleVisibility () {
    if (buttonTarget(this).style.display === 'none') {
        show(this);
    } else {
        hide(this);
    }
    checkStatus();
}

// Show/hide text within hide tags.
function showhide (event) {
    var hidebuttons = localShowHideButtons();

    if (!visible()) {
        for (var i = 0, ilen = hidebuttons.length; i < ilen; i++) {
            show(hidebuttons[i]);
        }
    } else {
        for (i = 0, ilen = hidebuttons.length; i < ilen; i++) {
            hide(hidebuttons[i]);
        }
    }

    checkStatus();
    if (event.preventDefault) {
        event.preventDefault();
    } else {
        event.returnValue = false;
    }
}

// Get the show/hide buttons for all individual comments
function localShowHideButtons () {
    return document.querySelectorAll('.button2');
}

// Given a show/hide button, this returns the element whose
// style.display should be toggled
function buttonTarget (hidebutton) {
    var ancestor = hidebutton.parentNode.parentNode;
    return ancestor.querySelectorAll('.quotecontent')[0].
        getElementsByTagName('div')[0];
}

// Capability testing.

if (document.querySelectorAll) {
    if (window.addEventListener) {
        window.addEventListener('load', addLink, false);
    } else if (window.attachEvent) {
        window.attachEvent('load', addLink);
    }
}