Is it possible to modify/remove an <body onload="..."> event via GreaseMonkey?
The code in question is this:
<body onload="if (document.body.scrollIntoView && (window.location.href.indexOf('#') == -1 || window.location.href.indexOf('#post') > -1)) { fetch_object('currentPost').scrollIntoView(true); }">
I would like to completely prevent it from executing (it is an annoying vBulletin feature to scroll to the post even if no hash is present in the URL which apparently also triggers when using the "back" button).
Yes, you can intercept <body onload="..." ... by overwriting it as soon as the DOM is interactively available to Greasemonkey (Probably can be made to work in Chrome, too, but not tested).
This works:
// ==UserScript==
// #name _Block inline onload function
// #namespace _pc
// #include http://YOUR_SERVER/YOUR_PATH/*
// #run-at document-start
// ==/UserScript==
document.addEventListener ("readystatechange", FireWhenReady, true);
function FireWhenReady () {
this.fired = this.fired || false;
if ( document.readyState != "uninitialized"
&& document.readyState != "loading"
&& ! this.fired
) {
this.fired = true;
document.body.onload = function () {
console.log ("body onload intercepted.");
};
}
}
Related
This script works just fine in Tampermonkey on both Chrome and Firefox, but doesn't work in Greasemonkey on Firefox. When I say it doesn't work I mean the button does not show up on the page. I'm using Chrome 61.0.3163.79 and Firefox 52.3.0.
The firefox console shows this warning but I'm not sure if it's relevant:
unreachable code after return statement[Learn More] jquery-1.3.2.min.js
Here's the code. Using greasemonkey on Firefox, I see "create button" in the console, but not "button has been created", which makes me think something is going wrong with the button creation. Any help greatly appreciated!
// ==UserScript==
// #name MyScript
// #namespace MyNS
// #description Adds a button to insert text into 2 text boxes
// #version 0.1
// #include *Removed for confidentiality*
// #compatible Greasemonkey
// ==/UserScript==
var descriptionText = "myDescription";
var testingText = "myTesting";
// Check if jQuery's loaded
function GM_wait() {
if (typeof unsafeWindow.jQuery == 'undefined') { window.setTimeout(GM_wait,100); }
else { $ = unsafeWindow.jQuery; init(); }
}
// All your GM code must be inside this function
function init() {
var description = $('#description');
var testingDone = $('#testing_done');
function insertText(template, editor) {
if (template) {
if (!editor._editing) {
editor.startEdit();
}
editor._field.queue(function() {
var oldVal = editor._field.val();
editor._field.val(template + (oldVal ? "\n" : "") + oldVal);
editor._field.keyup();
editor._field.dequeue();
});
}
}
function createButton(editor) {
console.log("create button:");
editor._insertTextButton = $('<input/>')
.attr('type', 'button')
.attr('value', 'Insert CR Template')
.css('margin-left', '1em')
.click(function() {
insertText(testingText, testingDoneEditor);
insertText(descriptionText, descriptionEditor);
});
console.log("button has been created");
editor._insertTextButton.insertAfter(editor._editIcon);
}
descriptionEditor = description.data('inlineEditor');
testingDoneEditor = testingDone.data('inlineEditor');
createButton(descriptionEditor);
}
GM_wait();
I'm trying to launch the cast api from a chrome extension that i'm writing. When I run this same code in a regular old HTML file on my webserver, it works perfectly. It doesn't work when I use this code in the popup of my extension. The requestSession call doesn't work at all in that case and nothing seems to happen after it's called.
I believe the expected behaviour is that the google cast extension will show the device list popup. Here is my javascript and html. Most of it is copied right out of CastHelloVideo-chrome.
HTML:
<html>
<head>
<title>Popup</title>
<style>
body {
min-width:5px;
overflow-x:hidden;
}
</style>
<script type="text/javascript" src="https://www.gstatic.com/cv/js/sender/v1/cast_sender.js"></script>
</head>
<body>
<button type="button" id="castButton">Cast!</button>
</body>
<script type="text/javascript" src="popup.js"></script>
</html>
Javascript:
//Constants
var applicationID = "<App ID>";
var session;
var currentMediaSession;
///////////////////////////////////////////////////////////////////
//Chromecast API
///////////////////////////////////////////////////////////////////
if (!chrome.cast || !chrome.cast.isAvailable) {
setTimeout(initializeCastApi, 1000);
}
function loadMedia() {
if (!session) {
console.log("no session");
return;
}
var mediaInfo = new chrome.cast.media.MediaInfo('http://commondatastorage.googleapis.com/gtv-videos-bucket/big_buck_bunny_1080p.mp4');
mediaInfo.contentType = 'video/mp4';
var request = new chrome.cast.media.LoadRequest(mediaInfo);
request.autoplay = false;
request.currentTime = 0;
session.loadMedia(request,
onMediaDiscovered.bind(this, 'loadMedia'),
onMediaError);
}
/**
* callback on success for loading media
* #param {Object} e A non-null media object
*/
function onMediaDiscovered(how, mediaSession) {
console.log("new media session ID:" + mediaSession.mediaSessionId);
currentMediaSession = mediaSession;
}
/**
* callback on media loading error
* #param {Object} e A non-null media object
*/
function onMediaError(e) {
console.log("media error");
}
//////////////////////////////////////////////////////////////////
//UI
//////////////////////////////////////////////////////////////////
var castbutton = document.getElementById("castButton");
castButton.onclick=function(){
window.close();
chrome.cast.requestSession(onRequestSessionSuccess, onLaunchError);
// loadMedia();
};
//////////////////////////////////////////////////////////////////
//Helper Functions
//////////////////////////////////////////////////////////////////
function initializeCastApi() {
var sessionRequest = new chrome.cast.SessionRequest(applicationID);
var apiConfig = new chrome.cast.ApiConfig(sessionRequest,
sessionListener,
receiverListener);
chrome.cast.initialize(apiConfig, onInitSuccess, onError);
}
function sessionListener(e) {
console.log('New session ID: ' + e.sessionId);
session = e;
}
function receiverListener(e) {
console.log(e);
}
function onInitSuccess() {
console.log("init success");
}
function onError() {
console.log("error");
}
function onSuccess(message) {
console.log(message);
}
function onRequestSessionSuccess(e) {
session = e;
console.log("session created");
}
function onLaunchError(e) {
console.log(e.description);
}
I think this may be caused because I'm trying to run this out of the popup of my extension. Maybe chrome doesn't allow multiple plugins to show their (the device list is google cast's popup) popup window's at the same time? I've tried closing the popup before executing the requestSession call, but it still doesn't work. Anyone have any ideas?
Invoking requestionSession API call within a Chrome extension is not supported. That's why you cannot get a list of devices.
In any case this method call only works from a regular web page and it triggers the extension to show a pop-up of Cast devices. That's the only current way it's supposed to work.
Here is my situation, I need to speed up the function running time, so setInterval is not a wise choose, right? Since it will cost at least 4ms for each time.
So, may I change setInterval function to requestAnimationFrame, but I don't quite understand how the requestAnimationFrame works.
For example
// some code here
var interval = setInterval(doSomething, 10)
var progress = 0
function doSomething(){
if (progress != 100){
// do some thing here
}else{
clearInterval(interval)
}
}
and how can I apply requestAnimationFrame?
I think the key to understand requestAnimationFrame lies in paul Irish's explanation:
Any rAFs queued in a rAF will be executed in the next frame
from requestAnimationFrame Scheduling For Nerds
var rafReference;
var progress = 0;
function doSomething(){
// only run 100 times
if (progress < 100){
/* do what you wanna do here */
progress++;
//recursively calls it self as requestAnimationFrame's callback
rafReference = requestAnimationFrame(doSomething) // passed as reference
}else{
cancelAnimationFrame(rafReference)
}
}
//starting the recursion
requestAnimationFrame(doSomething)
Looks better in a fiddle-->just the code,no animation
Every thing is commented inside the code for simplification.No need of using setInterval.
Just use cancelAnimationFrame when we are suppose to clear interval.
// This makes sure that there is a method to request a callback to update the graphics for next frame
var requestAnimationFrame =
window.requestAnimationFrame || // According to the standard
window.mozRequestAnimationFrame || // For mozilla
window.webkitRequestAnimationFrame || // For webkit
window.msRequestAnimationFrame || // For ie
function (f) { window.setTimeout(function () { f(Date.now()); }, 1000/60); }; // If everthing else fails
var cancelAnimationFrame =
window.cancelAnimationFrame ||
window.mozCancelAnimationFrame ||
window.webkitCancelAnimationFrame ||
window.msCancelAnimationFrame;
// your code here
var progress = 0;
function doSomething() {
if (progress != 100) {
// do something here
var myAnimation = requestAnimationFrame(doSomething);
} else {
// don't use clearInterval(interval) instead when you know that animation is completed use cancelAnimationFrame()
cancelAnimationFrame(myAnimation);
}
}
Some Links worth a read-->
CreativeJs---the best explanation any one could give,Every begineer must read
CancelAnimationFrame
link 3-->in context of your question
I found this fiddle on google,quite the same that you want.
Other things that you should know:
RAF is still in the development stage.
Why doesn't jQuery use requestAnimationFrame?
I'm trying to modify a page that uses MooTools to add event-listeners to some fields, like so:
$('inputPassword').addEvents({
keypress: function(){
new WorkspaceModalbox({'href':'someurl.phtml', 'width':500, 'height':140, 'title':'foo'});
}
});
I need to remove this behavior using Greasemonkey/Tampermonkey. I tried:
// ==UserScript==
// #require http://userscripts.org/scripts/source/44063.user.js
// ==/UserScript==
window.addEventListener("load", function(e) {
$('inputPassword').removeEvents('keypress');
}, false);
where removeEvents is a function from MooTools, the opposite one to addEvents.
But the script doesn't work. (Editor's note: There are no reported errors)
Why?
Is it because my code is executed before the code from the real page?
The event was installed in page scope but the script is running in script scope. Also, depending on the browser and on the #grant settings, there may be a sandbox involved.
So, to remove that event, you must use script injection (Moo tools doesn't seem to play nice with unsafeWindow.)
This script works on both Greasemonkey and Tampermonkey:
// ==UserScript==
// #name _Remove a Moo event listener
// #include http://YOUR_SERVER.COM/YOUR_PATH/*
// #grant GM_addStyle
// ==/UserScript==
/*- The #grant directive is needed to work around a design change
introduced in GM 1.0. It restores the sandbox.
*/
window.addEventListener ("load", function (e) {
addJS_Node ("$('inputPassword').removeEvents('keypress');");
}, false);
//-- addJS_Node is a standard(ish) function
function addJS_Node (text, s_URL, funcToRun, runOnLoad) {
var D = document;
var scriptNode = D.createElement ('script');
if (runOnLoad) {
scriptNode.addEventListener ("load", runOnLoad, false);
}
scriptNode.type = "text/javascript";
if (text) scriptNode.textContent = text;
if (s_URL) scriptNode.src = s_URL;
if (funcToRun) scriptNode.textContent = '(' + funcToRun.toString() + ')()';
var targ = D.getElementsByTagName ('head')[0] || D.body || D.documentElement;
targ.appendChild (scriptNode);
}
Note that there is no need to #require-in Moo tool just for this, since the page's instance of Moo tools must be the one to remove the event(s).
This is the code which i used for window.onbeforeunload
<head>
<script>
window.onbeforeunload = func;
function func()
{
var request = new XMLHttpRequest();
request.open("POST", "exit.php", true);
request.onreadystatechange = stateChanged;
request.send(null);
}
function stateChanged()
{
if (request.readyState == 4 || request.readyState == "complete")
alert("Succes!");
}
</script>
</head>
this works with IE and Mozilla but does not work with Chrome..... please help......
thanks in advance.....
It seems that the only thing you can do with onbeforeunload in recent version of Chrome is to set the warning message.
window.onbeforeunload = function () {
return "Are you sure";
};
Will work. Other code in the function seems to be ignored by Chrome
UPDATE: As of Chrome V51, the returned string will be ignored and a default message shown instead.
Know I'm late to this, but was scratching my head why my custom beforeunload message wasn't working in Chrome and was reading this. So in case anyone else does the same, Chrome from Version 51 onwards no longer supports custom messages on beforeunload. Apparently it's because the feature has been misused by various scams. Instead you get a predefined Chrome message which may or may not suit your purposes. More details at:
https://developers.google.com/web/updates/2016/04/chrome-51-deprecations?hl=en#remove-custom-messages-in-onbeforeload-dialogs
Personally do not think the message they've chosen is a great one as it mentions leaving the site and one of the most common legitimate uses for onbeforeunload is for dirty flag processing/checking on a web form so it's not a great wording as a lot of the time the user will still be on your site, just have clicked the cancel or reload button by mistake.
You should try this:
window.onbeforeunload = function(e) {
e.returnValue = 'onbeforeunload';
return 'onbeforeunload';
};
This works on latest Chrome. We had the same issue the e.returnValue with value of onbeforeunload solved my problem.
Your code should be like this:
<head>
<script>
window.onbeforeunload = function(e) {
e.returnValue = 'onbeforeunload';
func();
return ''onbeforeunload'';
};
function func()
{
var request = new XMLHttpRequest();
request.open("POST", "exit.php", true);
request.onreadystatechange = stateChanged;
request.send(null);
}
function stateChanged()
{
if (request.readyState == 4 || request.readyState == "complete")
alert("Succes!");
}
</script>
</head>
Confirmed this behavior on chrome 21.0.1180.79
this seems to work with the same restritions as XSS, if you are refreshing the page or open a page on same domain+port the the script is executed, otherwise it will only be executed if you are returning a string (or similar) and a dialog will be shown asking the user if he wants to leans or stay in the page.
this is an incredible stupid thing to do, because onunload/onbeforeunload are not only used to ask/prevent page changes.
In my case i was using it too save some changes done during page edition and i dont want to prevent the user from changing the page (at least chrome should respect a returning true or change the page without the asking if the return is not a string), script running time restrictions would be enought.
This is specially annoying in chrome because onblur event is not sent to editing elements when unloading a page, chrome simply igores the curent page and jumps to another. So the only change of saving the changes was the unload process and it now can't be done without the STUPID question if the user wants to change it... of course he wants and I didnt want to prevent that...
hope chrome resolves this in a more elegant way soon.
Try this, it worked for me:
window.onbeforeunload = function(event) {
event.returnValue = "Write something clever here..";
};
Try this. I've tried it and it works. Interesting but the Succes message doesn`t need confirmation like the other message.
window.onbeforeunload = function()
{
if ( window.XMLHttpRequest )
{
console.log("before"); //alert("before");
var request = new XMLHttpRequest();
request.open("POST", "exit.php", true);
request.onreadystatechange = function () {
if ( request.readyState == 4 && request.status == 200 )
{
console.log("Succes!"); //alert("Succes!");
}
};
request.send();
}
}
None of the above worked for me. I was sending a message from the content script -> background script in the before unload event function. What did work was when I set persistent to true (in fact you can just remove the line altogether) in the manifest:
"background": {
"scripts": [
"background.js"
],
"persistent": true
},
The logic is explained at this SO question here.
Current versions of Chrome require setting the event's returnValue property. Simply returning a string from the event handler won't trigger the alert.
addEventListener('beforeunload', function(event) {
event.returnValue = 'You have unsaved changes.';
});
I'm running Chrome on MacOS High Sierra and have an Angular 6 project whithin I handle the window.beforeunload an window.onbeforeunload events. You can do that, it's worked for me :
handleUnload(event) {
// Chrome
event.returnValue = true;
}
It show me an error when I try to put a string in event.returnValue, it want a boolean.
Don't know if it allows custom messages to display on the browser.
<script type="text/javascript">
window.addEventListener("beforeunload", function(e) {
e.preventDefault(); // firefox
e.returnValue = ''; // Chrome
});
</script>