Is there some JavaScript code I can execute to scroll to the top of the messages box on Facebook? So when you click 'see all' and go the main message page, if you scroll up it loads more messages. I want to force the it to keep scrolling up to keep loading messages. I've tried
document.body.scrollTop = document.documentElement.scrollTop = 0;
But that of course only scrolls to the top of the actual page. Any ideas on how to scroll the messages box up?
Select a conversation and try this script (load it through the console):
var autoLoad = {
messagesContainer: document.querySelector('#contentArea [role=main] .uiScrollableAreaContent'),
start: function (speed) {
var messagesContainer = this.messagesContainer,
loadMore = document.querySelector('[role=log] .pam.uiBoxLightblue.uiMorePagerPrimary');
speed = parseInt(speed, 10) || 1000;
clearInterval(this.interval);
this.interval = setInterval(function () {
messagesContainer.style.top = '0px';
loadMore.click();
}, speed);
},
stop: function () {
clearInterval(this.interval);
this.messagesContainer.style.top = '';
}
};
To start it, type:
// Takes a 'speed' parameter, defaults to 1000 milliseconds
autoLoad.start(1200);
And to stop it (necessary for the scrollbar to re-appear):
autoLoad.stop();
Explanation:
After exploring Facebook's DOM, I found some selectors that specifically target the elements that are needed for this to work:
The messages container, which holds the messages
The 'load more' link, that triggers facebook's script in charge of loading more messages.
The messages container scrollable area doesn't use native scrolling, instead, it uses bottom and top to set it's current scroll position.
So, if you want to scroll to the top, you set the container to top: '0', and since this way, the messages auto-load AJAX only triggers once, you need to trigger it manually after every scroll to top. I managed to do this simply by executing click in the link that triggers the AJAX.
I tried to get the most specific classes/selectors that I could find, and the ones that sounded more general, since I don't know if Facebook generates ids/classes dynamically in some way.
I tested this under Firefox and Chrome, explore the code a bit and change it to fit your needs. I hope this works for you as is, otherwise, you can use the DOM explorer to find the appropriate selectors.
I had to tweak the script to use "scrollTop" instead of "style.top".
var autoLoad = {
messagesContainer: document.querySelector('#globalContainer [role=main] .uiScrollableAreaContent'),
start: function (speed) {
var messagesContainer = this.messagesContainer,
loadMore = document.querySelector('#js_d');
speed = parseInt(speed, 10) || 1000;
clearInterval(this.interval);
this.interval = setInterval(function () {
messagesContainer.scrollTop = 0;
loadMore.scrollTop = 0;
/* loadMore.click(); */
}, speed);
},
stop: function () {
clearInterval(this.interval);
this.messagesContainer.style.top = '';
}
};
Nov 2021 #user4698813 code update:
var autoLoad = {
messagesContainer: document.querySelector('[role=main]'),
start: function (speed) {
var messagesContainer = this.messagesContainer,
loadMore = document.querySelector('[data-release-focus-from]');
speed = parseInt(speed, 10) || 1000;
clearInterval(this.interval);
this.interval = setInterval(function () {
messagesContainer.scrollTop = 0;
loadMore.scrollTop = 0;
/* loadMore.click(); */
}, speed);
},
stop: function () {
clearInterval(this.interval);
this.messagesContainer.style.top = '';
}
};
I'm trying to make an image drop up/down from a menu whenever the user clicks on the menu image which hasonClick="move()"in the tag. So far The image starts at the top of the page, behind the menu, so it is hidden, then slides down as intended. However, after the image reaches it's stopping point, clicking the menu again does nothing at all when I test the page in both IE and Chrome. In Dreamweaver, the code executes as intended, with the ability to slide the image up after it reaches the bottom and back down again. I've tried changing the call to setInterval() because I assumed that is where the problem was but nothing seems to be working. Why does Dreamweaver execute the code properly but not Chrome or IE?
var onMusic=false;
var id;
function move() {
if(!onMusic) {
moveDown()
}
else {
moveUp()
}
}
function moveUp() {
top=100
id = setInterval(function() {
top-=10 // update parameters
document.getElementById('guitar').style.top = top + 'px' // show frame
if (top <= -500) {// check finish condition
onMusic=false
clearInterval(id)
}
}, 10) // draw every 10ms
}
function moveDown() {
var top=-500
id = setInterval(function() {
top+=10 // update parameters
document.getElementById('guitar').style.top = top + 'px' // show frame
if (top == 100) {// check finish condition
onMusic=true
clearInterval(id)
}
}, 10) // draw every 10ms
}
id is only visible from the scope of the moveDown function. Make it global so that you can call clearInterval(id) in moveUp.
Change
function moveDown() {
var top=-500
var id = setInterval(function() {
to
var id;
function moveDown() {
var top=-500
id = setInterval(function() {
And changing the dom every tenth of millisecond (.1) might be a little extrem...
I think the problem was:
top=100
// should be
var top = 100;
You can try in the console to see what I mean:
>top = 12
12
> top
Window {top: Window, window: Window, location: Location, Proxy: Object, external: Object…}
But I cleaned it up a little more in jsfiddle:
http://jsfiddle.net/pNh57/1/
I'm trying to implement the marquee tag in jQuery by animation a set of images using animate() function, making them move to the right or left direction.
But, I couldn't figure out when a single image goes to the end of the screen returns individually to the other side.
Because I heard that the window size is not constant for every browser, So is there anyway to implement that?
this is what I came up so far(it's simple and basic):
$(document).ready(function(){
moveThumbs(500);
function moveThumbs(speed){
$('.thumbnails').animate({
right:"+=150"
}, speed);
setTimeout(moveThumbs, speed);
}
});
note: I searched in SO for related questions, but had no luck to find exact information for my specific issue.
Here's a basic script that moves an image across the screen and then resumes on the other side and adapts to the window width.
You can see it working here: http://jsfiddle.net/jfriend00/rnWa2/
function startMoving(img) {
var img$ = $(img);
var imgWidth = img$.width();
var screenWidth = $(window).width();
var amount = screenWidth - (parseInt(img$.css("left"), 10) || 0);
// if already past right edge, reset to
// just left of left edge
if (amount <=0 ) {
img$.css("left", -imgWidth);
amount = screenWidth + imgWidth;
}
var moveRate = 300; // pixels per second to move
var time = amount * 1000 / moveRate;
img$.stop(true)
.animate({left: "+=" + amount}, time, "linear", function() {
// when animation finishes, start over
startMoving(this);
})
}
$(document).ready(function() {
// readjust if window changes size
$(window).resize(function() {
$(".mover").each(function() {
startMoving(this);
});
});
});
I am newbie in JS. Right now i am working on an effect in which i want when page scroll first time then the natural motion animation starts but it's creating a problem because when i scroll the element animation became fast.
Check this more you got the idea.
http://jsfiddle.net/byvLy/
i know that this is a swinging box (figured it out due to the Math.sin())
however, you have to note that scrolling event is fired every few milliseconds during scrolling. in your code, you are calling animate and creating an interval every time the scroll event is fired. that's why your animation is jumpy;
try this instead:
$(function() {
$(window).on('scroll', function() {
swing.start('.cloud1, .cloud2');
});
var swing = (function() {
var animated = false;
function startAnimation(selector) {
if (!animated) {
var banner = $(selector);
var start = 0;
animated = true;
window.setInterval(function() {
banner.css('left', 100 * Math.sin(start) + 80);
start += 0.1;
}, 30);
}
}
return {
start: startAnimation
}
}());
});
Is it possible to detect, using JavaScript, when the user changes the zoom in a page?
I simply want to catch a "zoom" event and respond to it (similar to window.onresize event).
Thanks.
There's no way to actively detect if there's a zoom. I found a good entry here on how you can attempt to implement it.
I’ve found two ways of detecting the
zoom level. One way to detect zoom
level changes relies on the fact that
percentage values are not zoomed. A
percentage value is relative to the
viewport width, and thus unaffected by
page zoom. If you insert two elements,
one with a position in percentages,
and one with the same position in
pixels, they’ll move apart when the
page is zoomed. Find the ratio between
the positions of both elements and
you’ve got the zoom level. See test
case.
http://web.archive.org/web/20080723161031/http://novemberborn.net/javascript/page-zoom-ff3
You could also do it using the tools of the above post. The problem is you're more or less making educated guesses on whether or not the page has zoomed. This will work better in some browsers than other.
There's no way to tell if the page is zoomed if they load your page while zoomed.
Lets define px_ratio as below:
px ratio = ratio of physical pixel to css px.
if any one zoom The Page, the viewport pxes (px is different from pixel ) reduces and should be fit to The screen so the ratio (physical pixel / CSS_px ) must get bigger.
but in window Resizing, screen size reduces as well as pxes. so the ratio will maintain.
zooming: trigger windows.resize event --> and change px_ratio
but
resizing: trigger windows.resize event --> doesn’t change px_ratio
//for zoom detection
px_ratio = window.devicePixelRatio || window.screen.availWidth / document.documentElement.clientWidth;
$(window).resize(function(){isZooming();});
function isZooming(){
var newPx_ratio = window.devicePixelRatio || window.screen.availWidth / document.documentElement.clientWidth;
if(newPx_ratio != px_ratio){
px_ratio = newPx_ratio;
console.log("zooming");
return true;
}else{
console.log("just resizing");
return false;
}
}
The key point is difference between CSS PX and Physical Pixel.
https://gist.github.com/abilogos/66aba96bb0fb27ab3ed4a13245817d1e
Good news everyone some people! Newer browsers will trigger a window resize event when the zoom is changed.
I'm using this piece of JavaScript to react to Zoom "events".
It polls the window width.
(As somewhat suggested on this page (which Ian Elliott linked to): http://novemberborn.net/javascript/page-zoom-ff3 [archive])
Tested with Chrome, Firefox 3.6 and Opera, not IE.
Regards, Magnus
var zoomListeners = [];
(function(){
// Poll the pixel width of the window; invoke zoom listeners
// if the width has been changed.
var lastWidth = 0;
function pollZoomFireEvent() {
var widthNow = jQuery(window).width();
if (lastWidth == widthNow) return;
lastWidth = widthNow;
// Length changed, user must have zoomed, invoke listeners.
for (i = zoomListeners.length - 1; i >= 0; --i) {
zoomListeners[i]();
}
}
setInterval(pollZoomFireEvent, 100);
})();
This works for me:
var deviceXDPI = screen.deviceXDPI;
setInterval(function(){
if(screen.deviceXDPI != deviceXDPI){
deviceXDPI = screen.deviceXDPI;
... there was a resize ...
}
}, 500);
It's only needed on IE8. All the other browsers naturally generate a resize event.
There is a nifty plugin built from yonran that can do the detection. Here is his previously answered question on StackOverflow. It works for most of the browsers. Application is as simple as this:
window.onresize = function onresize() {
var r = DetectZoom.ratios();
zoomLevel.innerHTML =
"Zoom level: " + r.zoom +
(r.zoom !== r.devicePxPerCssPx
? "; device to CSS pixel ratio: " + r.devicePxPerCssPx
: "");
}
Demo
Although this is a 9 yr old question, the problem persists!
I have been detecting resize while excluding zoom in a project, so I edited my code to make it work to detect both resize and zoom exclusive from one another. It works most of the time, so if most is good enough for your project, then this should be helpful! It detects zooming 100% of the time in what I've tested so far. The only issue is that if the user gets crazy (ie. spastically resizing the window) or the window lags it may fire as a zoom instead of a window resize.
It works by detecting a change in window.outerWidth or window.outerHeight as window resizing while detecting a change in window.innerWidth or window.innerHeight independent from window resizing as a zoom.
//init object to store window properties
var windowSize = {
w: window.outerWidth,
h: window.outerHeight,
iw: window.innerWidth,
ih: window.innerHeight
};
window.addEventListener("resize", function() {
//if window resizes
if (window.outerWidth !== windowSize.w || window.outerHeight !== windowSize.h) {
windowSize.w = window.outerWidth; // update object with current window properties
windowSize.h = window.outerHeight;
windowSize.iw = window.innerWidth;
windowSize.ih = window.innerHeight;
console.log("you're resizing"); //output
}
//if the window doesn't resize but the content inside does by + or - 5%
else if (window.innerWidth + window.innerWidth * .05 < windowSize.iw ||
window.innerWidth - window.innerWidth * .05 > windowSize.iw) {
console.log("you're zooming")
windowSize.iw = window.innerWidth;
}
}, false);
Note: My solution is like KajMagnus's, but this has worked better for me.
⬤ The resize event works on modern browsers by attaching the event on window, and then reading values of thebody, or other element with for example (.getBoundingClientRect()).
In some earlier browsers it was possible to register resize event
handlers on any HTML element. It is still possible to set onresize
attributes or use addEventListener() to set a handler on any element.
However, resize events are only fired on the window object (i.e.
returned by document.defaultView). Only handlers registered on the
window object will receive resize events.
⚠️ Do resize your tab, or zoom, to trigger this snippet:
window.addEventListener("resize", getSizes, false)
function getSizes(){
let body = document.body
body.width = window.innerWidth
body.height = window.innerHeight
console.log(body.width +"px x "+ body.height + "px")
}
getSizes()
⬤ An other modern alternative: the ResizeObserver API
Depending your layout, you can watch for resizing on a particular element.
This works well on «responsive» layouts, because the container box get resized when zooming.
function watchBoxchange(e){
info.textContent = e[0].contentBoxSize[0].inlineSize+" x "+e[0].contentBoxSize[0].blockSize + "px"
}
new ResizeObserver(watchBoxchange).observe(fluid)
#fluid {
width: 200px;
height:100px;
overflow: auto;
resize: both;
border: 3px black solid;
display: flex;
flex-direction: column;
justify-content: center;
align-items: center;
font-size: 8vh
}
<div id="fluid">
<info id="info"></info>
</div>
💡 Be careful to not overload javascript tasks from user gestures events. Use requestAnimationFrame whenever you needs redraws.
I'd like to suggest an improvement to previous solution with tracking changes to window width. Instead of keeping your own array of event listeners you can use existing javascript event system and trigger your own event upon width change, and bind event handlers to it.
$(window).bind('myZoomEvent', function() { ... });
function pollZoomFireEvent()
{
if ( ... width changed ... ) {
$(window).trigger('myZoomEvent');
}
}
Throttle/debounce can help with reducing the rate of calls of your handler.
According to MDN, "matchMedia" is the proper way to do this https://developer.mozilla.org/en-US/docs/Web/API/Window/devicePixelRatio#Monitoring_screen_resolution_or_zoom_level_changes
it's a bit finicky because each instance can only watch one MQ at a time, so if you're interested in any zoom level change you need to make a bunch of matchers.. but since the browser is in charge to emitting the events it's probably still more performant than polling, and you could throttle or debounce the callback or pin it to an animation frame or something - here's an implementation that seems pretty snappy, feel free to swap in _throttle or whatever if you're already depending on that.
Run the code snippet and zoom in and out in your browser, note the updated value in the markup - I only tested this in Firefox! lemme know if you see any issues.
const el = document.querySelector('#dppx')
if ('matchMedia' in window) {
function observeZoom(cb, opts) {
opts = {
// first pass for defaults - range and granularity to capture all the zoom levels in desktop firefox
ceiling: 3,
floor: 0.3,
granularity: 0.05,
...opts
}
const precision = `${opts.granularity}`.split('.')[1].length
let val = opts.floor
const vals = []
while (val <= opts.ceiling) {
vals.push(val)
val = parseFloat((val + opts.granularity).toFixed(precision))
}
// construct a number of mediamatchers and assign CB to all of them
const mqls = vals.map(v => matchMedia(`(min-resolution: ${v}dppx)`))
// poor person's throttle
const throttle = 3
let last = performance.now()
mqls.forEach(mql => mql.addListener(function() {
console.debug(this, arguments)
const now = performance.now()
if (now - last > throttle) {
cb()
last = now
}
}))
}
observeZoom(function() {
el.innerText = window.devicePixelRatio
})
} else {
el.innerText = 'unable to observe zoom level changes, matchMedia is not supported'
}
<div id='dppx'>--</div>
You can also get the text resize events, and the zoom factor by injecting a div containing at least a non-breakable space (possibly, hidden), and regularly checking its height. If the height changes, the text size has changed, (and you know how much - this also fires, incidentally, if the window gets zoomed in full-page mode, and you still will get the correct zoom factor, with the same height / height ratio).
<script>
var zoomv = function() {
if(topRightqs.style.width=='200px){
alert ("zoom");
}
};
zoomv();
</script>
On iOS 10 it is possible to add an event listener to the touchmove event and to detect, if the page is zoomed with the current event.
var prevZoomFactorX;
var prevZoomFactorY;
element.addEventListener("touchmove", (ev) => {
let zoomFactorX = document.documentElement.clientWidth / window.innerWidth;
let zoomFactorY = document.documentElement.clientHeight / window.innerHeight;
let pageHasZoom = !(zoomFactorX === 1 && zoomFactorY === 1);
if(pageHasZoom) {
// page is zoomed
if(zoomFactorX !== prevZoomFactorX || zoomFactorY !== prevZoomFactorY) {
// page is zoomed with this event
}
}
prevZoomFactorX = zoomFactorX;
prevZoomFactorY = zoomFactorY;
});
Here is a clean solution:
// polyfill window.devicePixelRatio for IE
if(!window.devicePixelRatio){
Object.defineProperty(window,'devicePixelRatio',{
enumerable: true,
configurable: true,
get:function(){
return screen.deviceXDPI/screen.logicalXDPI;
}
});
}
var oldValue=window.devicePixelRatio;
window.addEventListener('resize',function(e){
var newValue=window.devicePixelRatio;
if(newValue!==oldValue){
// TODO polyfill CustomEvent for IE
var event=new CustomEvent('devicepixelratiochange');
event.oldValue=oldValue;
event.newValue=newValue;
oldValue=newValue;
window.dispatchEvent(event);
}
});
window.addEventListener('devicepixelratiochange',function(e){
console.log('devicePixelRatio changed from '+e.oldValue+' to '+e.newValue);
});
Here is a native way (major frameworks cannot zoom in Chrome, because they dont supports passive event behaviour)
//For Google Chrome
document.addEventListener("mousewheel", event => {
console.log(`wheel`);
if(event.ctrlKey == true)
{
event.preventDefault();
if(event.deltaY > 0) {
console.log('Down');
}else {
console.log('Up');
}
}
}, { passive: false });
// For Mozilla Firefox
document.addEventListener("DOMMouseScroll", event => {
console.log(`wheel`);
if(event.ctrlKey == true)
{
event.preventDefault();
if(event.detail > 0) {
console.log('Down');
}else {
console.log('Up');
}
}
}, { passive: false });
I'am replying to a 3 year old link but I guess here's a more acceptable answer,
Create .css file as,
#media screen and (max-width: 1000px)
{
// things you want to trigger when the screen is zoomed
}
EG:-
#media screen and (max-width: 1000px)
{
.classname
{
font-size:10px;
}
}
The above code makes the size of the font '10px' when the screen is zoomed to approximately 125%. You can check for different zoom level by changing the value of '1000px'.