Remove HTML text on scroll - html

I am trying to remove an element (<p>) from my HTML code as soon as the user scrolls down, and after the first scroll, it will not come back until a reload occurs. I couldn't find anything here, or on Google on this, so help would be appetited.
HTML
<body>
<div id="scrolltext">
<p>I go missing when the user scrolls, never to return</p>
</div>
</body>
I don't really know where to go from here, I think JavaScript would be needed, or at least a CSS scroll property of some sort.
I will add it in here that I am ok with using a combo of HTML CSS and JS.

You can use method remove()to remove any item from DOM inside window onscroll event.
Tag <p> will be removed after the first scroll, and will only appear again after reloading the page.
let p_remove = document.querySelector("#scrolltext p");
window.onscroll = function () {
p_remove.remove();
};
body {
height: 5000px;
}
<body>
<div id="scrolltext">
<p>I go missing when the user scrolls, never to return</p>
</div>
</body>

HTML and CSS cannot achieve dynamic DOM manipulation related to scrolling.
JavaScript can.
// Get (and cache) the desired Element from the DOM
const EL_scrolltext = document.querySelector("#scrolltext");
// Function to remove the element,
// and remove the expensive scroll listener
const removeScrollText = () => {
EL_scrolltext.remove(); // Remove element from DOM
window.removeEventListener("scroll", hideScrollText);
};
// Remove the Element once the user scrolls
window.addEventListener("scroll", removeScrollText);
body { min-height: 300vh; }
<div id="scrolltext">
<p>I go missing when the user scrolls, never to return</p>
</div>
Be aware that the above will not be triggered if the page cannot be scrolled (has no scrollbars)
Read more:
MDN: querySelector
MDN: addEventListener
MDN: removeEventListener
MDN: Scroll Event
MDN: Element Remove

Related

Position SVG lines over HTML elements, while still allowing interaction with the HTMl elements [duplicate]

I have a div that has background:transparent, along with border. Underneath this div, I have more elements.
Currently, I'm able to click the underlying elements when I click outside of the overlay div. However, I'm unable to click the underlying elements when clicking directly on the overlay div.
I want to be able to click through this div so that I can click on the underlying elements.
Yes, you CAN do this.
Using pointer-events: none along with CSS conditional statements for IE11 (does not work in IE10 or below), you can get a cross browser compatible solution for this problem.
Using AlphaImageLoader, you can even put transparent .PNG/.GIFs in the overlay div and have clicks flow through to elements underneath.
CSS:
pointer-events: none;
background: url('your_transparent.png');
IE11 conditional:
filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src='your_transparent.png', sizingMethod='scale');
background: none !important;
Here is a basic example page with all the code.
Yes, you CAN force overlapping layers to pass through (ignore) click events.
PLUS you CAN have specific children excluded from this behavior...
You can do this, using pointer-events
pointer-events influences the reaction to click-, tap-, scroll- und hover events.
In a layer that should ignore / pass-through mentioned events you set
pointer-events: none;
Children of that unresponsive layer that need to react mouse / tap events again need:
pointer-events: auto;
That second part is very helpful if you work with multiple overlapping div layers (probably some parents being transparent), where you need to be able to click on child elements and only that child elements.
Example usage:
.parent {
pointer-events:none;
}
.child {
pointer-events:auto;
}
<div class="parent">
I'm unresponsive
I'm clickable again, wohoo !
</div>
Allowing the user to click through a div to the underlying element depends on the browser. All modern browsers, including Firefox, Chrome, Safari, and Opera, understand pointer-events:none.
For IE, it depends on the background. If the background is transparent, clickthrough works without you needing to do anything. On the other hand, for something like background:white; opacity:0; filter:Alpha(opacity=0);, IE needs manual event forwarding.
See a JSFiddle test and CanIUse pointer events.
I'm adding this answer because I didn’t see it here in full. I was able to do this using elementFromPoint. So basically:
attach a click to the div you want to be clicked through
hide it
determine what element the pointer is on
fire the click on the element there.
var range-selector= $("")
.css("position", "absolute").addClass("range-selector")
.appendTo("")
.click(function(e) {
_range-selector.hide();
$(document.elementFromPoint(e.clientX,e.clientY)).trigger("click");
});
In my case the overlaying div is absolutely positioned—I am not sure if this makes a difference. This works on IE8/9, Safari Chrome and Firefox at least.
Hide overlaying the element
Determine cursor coordinates
Get element on those coordinates
Trigger click on element
Show overlaying element again
$('#elementontop').click(e => {
$('#elementontop').hide();
$(document.elementFromPoint(e.clientX, e.clientY)).trigger("click");
$('#elementontop').show();
});
I needed to do this and decided to take this route:
$('.overlay').click(function(e){
var left = $(window).scrollLeft();
var top = $(window).scrollTop();
//hide the overlay for now so the document can find the underlying elements
$(this).css('display','none');
//use the current scroll position to deduct from the click position
$(document.elementFromPoint(e.pageX-left, e.pageY-top)).click();
//show the overlay again
$(this).css('display','block');
});
I currently work with canvas speech balloons. But because the balloon with the pointer is wrapped in a div, some links under it aren't click able anymore. I cant use extjs in this case.
See basic example for my speech balloon tutorial requires HTML5
So I decided to collect all link coordinates from inside the balloons in an array.
var clickarray=[];
function getcoo(thatdiv){
thatdiv.find(".link").each(function(){
var offset=$(this).offset();
clickarray.unshift([(offset.left),
(offset.top),
(offset.left+$(this).width()),
(offset.top+$(this).height()),
($(this).attr('name')),
1]);
});
}
I call this function on each (new) balloon. It grabs the coordinates of the left/top and right/down corners of a link.class - additionally the name attribute for what to do if someone clicks in that coordinates and I loved to set a 1 which means that it wasn't clicked jet. And unshift this array to the clickarray. You could use push too.
To work with that array:
$("body").click(function(event){
event.preventDefault();//if it is a a-tag
var x=event.pageX;
var y=event.pageY;
var job="";
for(var i in clickarray){
if(x>=clickarray[i][0] && x<=clickarray[i][2] && y>=clickarray[i][1] && y<=clickarray[i][3] && clickarray[i][5]==1){
job=clickarray[i][4];
clickarray[i][5]=0;//set to allready clicked
break;
}
}
if(job.length>0){
// --do some thing with the job --
}
});
This function proofs the coordinates of a body click event or whether it was already clicked and returns the name attribute. I think it is not necessary to go deeper, but you see it is not that complicate.
Hope in was enlish...
Another idea to try (situationally) would be to:
Put the content you want in a div;
Put the non-clicking overlay over the entire page with a z-index higher,
make another cropped copy of the original div
overlay and abs position the copy div in the same place as the original content you want to be clickable with an even higher z-index?
Any thoughts?
I think the event.stopPropagation(); should be mentioned here as well. Add this to the Click function of your button.
Prevents the event from bubbling up the DOM tree, preventing any parent handlers from being notified of the event.
Just wrap a tag around all the HTML extract, for example
<a href="/categories/1">
<img alt="test1" class="img-responsive" src="/assets/photo.jpg" />
<div class="caption bg-orange">
<h2>
test1
</h2>
</div>
</a>
in my example my caption class has hover effects, that with pointer-events:none; you just will lose
wrapping the content will keep your hover effects and you can click in all the picture, div included, regards!
An easier way would be to inline the transparent background image using Data URIs as follows:
.click-through {
pointer-events: none;
background: url(data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7);
}
I think that you can consider changing your markup. If I am not wrong, you'd like to put an invisible layer above the document and your invisible markup may be preceding your document image (is this correct?).
Instead, I propose that you put the invisible right after the document image but changing the position to absolute.
Notice that you need a parent element to have position: relative and then you will be able to use this idea. Otherwise your absolute layer will be placed just in the top left corner.
An absolute position element is positioned relative to the first parent
element that has a position other than static.
If no such element is found, the containing block is html
Hope this helps. See here for more information about CSS positioning.
You can place an AP overlay like...
#overlay {
position: absolute;
top: -79px;
left: -60px;
height: 80px;
width: 380px;
z-index: 2;
background: url(fake.gif);
}
<div id="overlay"></div>
just put it over where you dont want ie cliked. Works in all.
This is not a precise answer for the question but may help in finding a workaround for it.
I had an image I was hiding on page load and displaying when waiting on an AJAX call then hiding again however...
I found the only way to display my image when loading the page then make it disappear and be able to click things where the image was located before hiding it was to put the image into a DIV, make the size of the DIV 10x10 pixels or small enough to prevent it causing an issue then hiding the containing div. This allowed the image to overflow the div while visible and when the div was hidden, only the divs area was affected by inability to click objects beneath and not the whole size of the image the DIV contained and was displaying.
I tried all the methods to hide the image including CSS display=none/block, opacity=0, hiding the image with hidden=true. All of them resulted in my image being hidden but the area where it was displayed to act like there was a cover over the stuff underneath so clicks and so on wouldn't act on the underlying objects. Once the image was inside a tiny DIV and I hid the tiny DIV, the entire area occupied by the image was clear and only the tiny area under the DIV I hid was affected but as I made it small enough (10x10 pixels), the issue was fixed (sort of).
I found this to be a dirty workaround for what should be a simple issue but I was not able to find any way to hide the object in its native format without a container. My object was in the form of etc. If anyone has a better way, please let me know.
I couldn't always use pointer-events: none in my scenario, because I wanted both the overlay and the underlying element(s) to be clickable / selectable.
The DOM structure looked like this:
<div id="outerElement">
<div id="canvas-wrapper">
<canvas id="overlay"></canvas>
</div>
<!-- Omitted: element(s) behind canvas that should still be selectable -->
</div>
(The outerElement, canvas-wrapper and canvas elements have the same size.)
To make the elements behind the canvas act normally (e.g. selectable, editable), I used the following code:
canvasWrapper.style.pointerEvents = 'none';
outerElement.addEventListener('mousedown', event => {
const clickedOnElementInCanvas = yourCheck // TODO: check if the event *would* click a canvas element.
if (!clickedOnElementInCanvas) {
// if necessary, add logic to deselect your canvas elements ...
wrapper.style.pointerEvents = 'none';
return true;
}
// Check if we emitted the event ourselves (avoid endless loop)
if (event.isTrusted) {
// Manually forward element to the canvas
const mouseEvent = new MouseEvent(event.type, event);
canvas.dispatchEvent(mouseEvent);
mouseEvent.stopPropagation();
}
return true;
});
Some canvas objects also came with input fields, so I had to allow keyboard events, too.
To do this, I had to update the pointerEvents property based on whether a canvas input field was currently focused or not:
onCanvasModified(canvas, () => {
const inputFieldInCanvasActive = // TODO: Check if an input field of the canvas is active.
wrapper.style.pointerEvents = inputFieldInCanvasActive ? 'auto' : 'none';
});
it doesn't work that way. the work around is to manually check the coordinates of the mouse click against the area occupied by each element.
area occupied by an element can found found by 1. getting the location of the element with respect to the top left of the page, and 2. the width and the height. a library like jQuery makes this pretty simple, although it can be done in plain js. adding an event handler for mousemove on the document object will provide continuous updates of the mouse position from the top and left of the page. deciding if the mouse is over any given object consists of checking if the mouse position is between the left, right, top and bottom edges of an element.
Nope, you can't click ‘through’ an element. You can get the co-ordinates of the click and try to work out what element was underneath the clicked element, but this is really tedious for browsers that don't have document.elementFromPoint. Then you still have to emulate the default action of clicking, which isn't necessarily trivial depending on what elements you have under there.
Since you've got a fully-transparent window area, you'll probably be better off implementing it as separate border elements around the outside, leaving the centre area free of obstruction so you can really just click straight through.

How to start from top after page change when using neon-animated-pages

When using neon-animated-pages if the page change event is triggered when you are not at the top of the current page, it will switch to the new page equally as far down the page. The default behavior should be to switch pages and show the top of the new page.
Is there a workaround to scroll to the top of the page after the new page is loaded?
I was able to work around it by setting the scrollTop to the element that contained the neon-animated-pages.I do this from the function that is called when I press on the button that changes my neon-animated-page.
document.querySelector('my-container').scrollTop = 0;
in my experience it is best for each page to have their own paper-header-panel, toolbar and ect. then when you change pages the next page will be # the top and the page you are leaving will have a memory of the scroll location when you left the page. This way seemed to have a better user experience for me.
<neon-animated-pages selected="{{page}}">
<neon-animatable>
<paper-header-panel>
<paper-toolbar></paper-toolbar>
//page 1
</paper-header-panel>
</neon-animatable>
<neon-animatable>
<paper-header-panel>
<paper-toolbar></paper-toolbar>
// page 2
</paper-header-panel>
</neon-animatable>
</neon-animated-pages>
only other real option is to use the event fired when neon animation ends.
<paper-header-panel id="panel">
Polymer({
is: 'custom-element',
listeners: {
'neon-animation-finish': '_onNeonAnimationFinish'
},
_onNeonAnimationFinish: function(e) {
document.querySelector('#panel').scroller().scrollTop = 0;
// or if panel is in same element
this.$.panel.scroller().scrollTop = 0;
}
});
this method combined with other functions ran after the animation cause my apps animations to look kind of janky.. this may not always be the case just my experience.
This is solvable in CSS. What you need to do is to create an individual scrolling context within each page. To do so, set the following:
HTML:
<paper-header-panel>
<paper-toolbar></paper-toolbar>
<neon-animated-pages selected="{{page}}">
<neon-animatable>
<div class="wrapper>
// Page 1
</div>
</neon-animatable>
<neon-animatable>
<div class="wrapper>
// Page 2
</div>
</neon-animatable>
</neon-animated-pages>
CSS:
.wrapper {
position: absolute;
height: 100%;
overflow-y: scroll; /* Not always required depending on the stacking context of your site */
}
neon-animatable {
height: 100%;
}
neon-animated-pages {
height: 100%;
}
The great thing about this solution is that each page remembers it's previous scrolling position – so if you scroll down in page 1, jump to page 2, scroll around in page 2 and jump back to page 1, you'll return where you left in page 1.
Add this to the change event listener:
$('#mainContainer').scrollTop(0);
For instance:
$('paper-tabs paper-tab').click(function(){
$('#mainContainer').scrollTop(0);
scope.selected = $('paper-tabs paper-tab').index(this)
});
Your neon animated / iron pages are likely within a paper-header-panel (common if using the Polymer Starter Kit).
See https://github.com/PolymerElements/polymer-starter-kit/issues/285

mouseLeave event never triggered

I'm trying to develop an overwolf app and am having issues receiving mouseLeave events.
Overwolf App:
<div id="menu" onMouseDown="dragMove();">
<div id="close" onclick="closeWindow();"></div>
</div>
<iframe src="URL_to_Webpage"></iframe>
<div id="scale" onmousedown="dragResize('BottomLeft');"></div>
<div id="sliderBg">
<div id="slider"></div>
</div>
The menu, close, scale and slider elements are overlayed ("position: absolute; left:...") over the iframe and work as window control elements (scaling, closing,...)
Webpage (iframe content):
$('html').hover(function() {
$(this).addClass('hover');
}, function() {
$(this).removeClass('hover');
});
I always get the hover class applied to my iframe as expected. CSS :hover selectors get applied as well.
The mouseLeave event though is only triggered, when leaving the iframe without "touching" the overlayed window control elements.
So if I touch those elements on my way out with my mouse, the "hover" class isn't removed (event simply not triggered) and all things applied with a css ":hover" selector aren't removed either.
Any help would be appreciated
Try add 'id' name on the iframe and imstead of directly using html.
I would like to see how it works to fully picture what you want to do.
Could you please paste your code at http://jsbin.com and let me know the link?

link to anchor near bottom of page

I'm doing some documentation where I make heavy use of anchors for linking between pages on a wiki.
see here:
http://code.google.com/p/xcmetadataservicestoolkit/wiki/ServicesExplained#Platform_Data_Structures
The feature that really makes this work well is when the browser shows the anchor at the absolute top of the pane. When it gets confusing is when linking to an anchor shows the anchor half-way down the page since the page is scrolled down all the way
see here:
http://code.google.com/p/xcmetadataservicestoolkit/source/browse/trunk/mst-common/src/java/xc/mst/utils/Util.java#227
My solution in the wiki (first link) was to put a blank image at the bottom of the page simply to make the browser show the anchor right at the top. Is there a better way to do this? Is there a way to do it in the second link (in which I can't add a blank image)?
Putting a blank image at the bottom of your page is a bad idea, since it will expand your document to a unnecessary height.
You could throw in some javascript to apply an effect to the anchor you just travelled to, to highlight it wherever it is.
Without altering the height of your document (i.e. adding extra padding at bottom), you'll always have this issue.
However, using bit of JS/jQuery, the user experience can be improved considerably:
On clicking a named anchor:
Instead of jumping in a flash (broswer's default behavior), add a smooth scroll
add an highlight to indicate current selection (this helps tremendously in 2nd case as the user can clearly see what is current)
Created a demo to illustrate the concepts: http://jsfiddle.net/mrchief/PYsyN/9/
CSS
<style>
.current { font-weight: bold; }
</style>
JS
function smoothScroll(elemId) {
// remove existing highlights
$('.current').css({backgroundColor: "transparent"}).removeClass('current');
var top = $(elemId).offset().top;
// do a smooth scroll
$('html, body').animate({scrollTop:top}, 500, function(){
// add an highlight
$(elemId).animate({backgroundColor: "#68BFEF" }, 500, function () {
// keep tab of current so that style can be reset later
$(elemId).addClass('current');
});
});
}
// when landing directly
if (document.location.hash) {
smoothScroll(document.location.hash);
}
$('a[href*="#"]').click(function() {
// utilizing the fact that named anchor has a corresponding id element
var elemId = $(this).attr('href');
smoothScroll(elemId);
});
You can create a absolutre positioned pseudo-element with a great height to targeted block using just the following CSS (for the second link in your post:
#nums td:target a::before {
content: '';
position: absolute;
height: 700px;
}
The height must be around the height of the viewport, so the best solution is to create these styles on the fly using js. But if you don't wan't to use js, just use height: 1000px or more — if you don't mind a gap at the bottom of course.
The best part: it's only CSS and there would be no gap when no anchors are targeted.
Edit: just a sneak peek into the future: if the vw/vh units would come to other browsers (now it's only in IE9), this could be awesomely done with just CSS using height: 100vh :)
You could use Javascript / jQuery to create a white div that has the necessary height needed to put your element at the top of the browser window, and you could even remove this upon scrolling away.
However I would highly recommend against doing so as this will expand your page where it isn't needed. It's a lot smarter to simply style the tag upon going there (through Javascript / jQuery) so it pops out to the viewer, for instance by setting the font-weight to bold or changing the background-color.
I would probably use a combination of jQuery and PHP for this:
PHP(somewhere right after your <body> element):
<?php
$anchor = explode('#', $_SERVER['REQUEST_URI']);
$anchor = $anchor[1];
echo '<div id="selected-anchor" anchor="'.$anchor.'"></div>';
?>
And then the jQuery:
<script type="text/javascript">
$(function(){
$('#selected-anchor').css('background-color', '[Whatever highlight color you want]');
});
</script>
Hope this helps.

Printing Scrolled Divs

I have a web page that displays a long line graph inside a div with overflow-x: scroll.
This works well as a web page allowing the use to scroll back and forward through the graph.
However, when printing the page the scroll position is reset to zero.
Is there a way to overcome this?
I think you're going to have to specify an alternate CSS for printing where you somehow need to remove the overflow:
<link rel="stylesheet" type="text/css” href="sheet.css" media="print" />
However, maybe there is an approach with JavaScript or even Flash? If I understand correctly, you only want to have a part of the graph printed (the one "selected" by the user?) and not the full one? I'm pretty sure that's not possible with plain HTML/CSS, but I strongly believe that Flash or maybe JavaScript/AJAX (to only load a part of the image at a time) can solve it.
You can't do this in plain CSS -- you will have to reimplement the scrolling using your Javascript UI library of choice to get what you want.
The user state of the scrollbar isn't used when printing (think about it, if you're scrolled 3 screens down a page and hit "print" does it make sense for the browser to only print the part of the document that's in your window at the time?). However, if you use JS, which actually manipulates the DOM (i.e. sets the x-position offset to -293 if the person has scrolled right 293 pixels, just like style="left: -293px; overflow: hidden;" in CSS), then it will show up as such in printed documents.
My suggestion is, unless the graphs are very wide, just skip all of this nonsense and use a printer stylesheet with width: 100% for the graph's <div> so the graph just shrinks to page width.
A simple approach would be to have some javascript which posts back to your page with the user's selected scroll position on a link saying something like 'setup for printing'. Then the server side returns a page with the graph relatively positioned at the scroll position with overflow:hidden to clip the graph appropriately.
Of course this would not work for users with javascript disabled - if you want to support this you would need the user to specify the scroll position in something like a text input element and submit button which you hid with javascript when enabled.
You need to temporarily turn the scroll position of the parent into a negative margin of the child, and put that parent as overflow:hidden.
Here's how to do it in Javascript (which is the only way, css cannot do that)
Note that you will need something to execute printDone() after the printing to restore everything as normal. You could trigger it with a wheel event e.g. because the user will only have a problem when trying to scroll. Or you can just put a button as I did, and show it only when printGo() is called.
<html>
<head>
<style>
#wrapper {
width:800px;
overflow-x:scroll;
}
#content {
width:2000px;
border:2px solid red;
}
#media print { /* This overwrites the css when printing */
#wrapper {
overflow-x:hidden;
}
}
</style>
</head>
<body>
Print<br>
I'm done printing!
<div id=wrapper>
<div id=content>
Hello this is my content.
</div>
</div>
<script>
var wrapper = document.getElementById('wrapper');
var content = document.getElementById('content');
var scrollPos;
function printGo(){
scrollPos = wrapper.scrollLeft; // Save scroll position
wrapper.scrollLeft = 0;
wrapper.style.overflowX = 'hidden'; // Optional since css does it
content.style.marginLeft = -scrollPos+'px'; // Put it as a negative margin of child instead
window.print();
}
function printDone(){
wrapper.scrollLeft = scrollPos; // Restore scroll position
wrapper.style.overflowX = 'scroll'; // Optional since css does it
content.style.marginLeft = '';
}
</script>
</body></html>