I'm trying to highlight some text in a div, with the highlight being a fixed line in said text. So far I've got a very simple solution that uses two divs, one that houses the text, and the other acting as the highlight, and as you scroll the text, it will pass through the highlight div.
HTML is as follows:
<div id="test">
text...
</div>
<div id="highlight"></div>
CSS is:
#highlight {
position: fixed;
top: 50%;
width: 100%;
background-color: #ccff00;
height: 30px;
opacity: 0.6;
}
#test{
position: absolute;
font-size: 30px;
top: 50%;
}
A demo of it can be found here
I was wondering if anyone knows how to make it so that scrolling the text can be done in a way where as a user scrolls, the next line becomes highlighted. Currently it scrolls normally, so the highlight may miss a line, or not highlight a complete line. Additionally, I was wondering how it would be best to make the text scroll all the way to the bottom. Would adding a margin of the same size as the offset at the top work? Alternative solutions for any of this would be appreciated as well.
Try adding an event listener to the window on scroll. Then calculate the offset by taking the scrollY % line-height and set the highlight top margin to the negative of that value.
JavaScript below:
var highlight = document.querySelector("#highlight");
window.addEventListener('scroll', function(e){
var y = window.scrollY;
var offset = y % 30;
highlight.style.marginTop = - y % 30 + "px";
});
See Working Fiddle
Not sure if this
https://jsfiddle.net/ok0x3apo/6/ is what you're looking for
You can see that I'm remodifying the entered text, to get line by line highlight as page scrolls.
var el = document.getElementById("text"),
content = el.innerHTML.replace(/ |^\s+|\s+$/g,""),
lines = content.split(/\./);
var html = "";
for(var i in lines){
html+="<p class='clear_display' id='id_"+i+"'>"+lines[i]+".</p>";
};
document.getElementById("text").innerHTML=html;
You can make changes to the "clear_display" class on how you prefer to have the text block.
function calledEveryScroll() {
var scrollPosition = $(window).scrollTop();
for(var i in lines){
var currentSection = document.querySelector("#id_"+i+"");
var sectionTop = currentSection.offsetTop;
if (scrollPosition<=0){
$(".clear_display").removeClass('active');
document.querySelector("#id_0").className += " active";
}
if (scrollPosition >= sectionTop-50) {
$(".clear_display").removeClass('active');
if (!$(currentSection).hasClass('active')) {
$(currentSection).addClass('active');
if(previous){
if(currentSection.offsetTop==previous.offsetTop){
$(previous).addClass('active');
}
}
var previous = currentSection;
}
//return false;
}
}
}
function resizing(){
var offset =100;
var bottom = $(window).height()-offset;
$('#text').css('margin-bottom',bottom);
}
This function checks each line when page scrolls.For the scroll to reach the bottom I'm calculating the margin-bottom.Hope it helps.
Related
I want to try the same effect of this site but am getting lost in action on how to implement this animation.
When the user starts scrolling, the images in the header zoom in, the scrolling tab(vertical) does not move, up to a point which another image shows up, and only afterward the scroll bar starts working.
How can I achieve this animation when scrolling?
At the moment, what I thought was: to get the pixel value of the DOM when am scrolling, as well as the height of the div I want to target.
While the value of the DOM is less than the height of the box, the scale value should change based on the scrolling value.
The JS looks like this:
<script>
$(window).scroll(function() {
var initial_scroll = $('html').scrollTop();
var firstbox_height = $('#firstbox').height();
// console.log(firstbox_height);
while(initial_scroll < firstbox_height){
var sum = firstbox_height + ((firstbox_height * 0.01) / 100);
$('img').css({
// "transform": "scale(" + sum + ")"
});
}
});
</script>
I seem to be going into an infinite loop.
My pen is here
Here's a working sample. It's not flawless, it bugs when you scroll just a little back and forth at the top, the text size might change in the wrong direction. Also it doesn't work when scrolling with arrow keys. But what it does is that it should give you the idea on how to proceed.
There's probably a cleaner, nicer and more concise way to do this, but this is one way.
To get a perfectly working one, I think you might have to place a transparent <div> over the one that changes, just to keep track of the position and hence the direction.
Fiddle here: https://jsfiddle.net/codesam/nedj3ubx/53/
HTML:
<body>
<div id="box">
Text
</div>
<p id="direction">
</p>
</body>
CSS:
body {
height: 200vh;
}
#box {
width: 100%;
height: 50vh;
background-color: black;
color: white;
font-size: 72px;
}
jQuery:
$(document).ready(function(){
var initialScroll = -1;
var size;
$(window).on('scroll touchmove mousewheel', function(e){
var currentScroll = $(window).scrollTop();
if (currentScroll > initialScroll) {
$("#direction").text("down");
size = parseInt($("#box").css("font-size"));
if (size > 10) {
$("#box").css("font-size", "-=2");
e.preventDefault();
e.stopPropagation();
return false;
}
}
else if (currentScroll < initialScroll) {
$("#direction").text("up");
}
else if (currentScroll == 0 && initialScroll == 0) {
size = parseInt($("#box").css("font-size"));
if (size < 72) {
$("#box").css("font-size", "+=2");
e.preventDefault();
e.stopPropagation();
return false;
}
}
initialScroll = currentScroll;
});
});
I have this code:
<span><img id="user" src="http://placehold.it/100x100" alt="img"></span>
<span><h2 id="textToChange">text here</h2></span>
When I change #textToChange the #user moves automatically because the text changes and because it's a span it moves it. I would like to animate #user so it will move in a linear animation instead of just getting to the x value.
Is something like to possible to achieve or am I crazy? Thanks.
This is an interesting little problem. Let me break it down into steps:
Find the image's current position
Find where it needs to move to
Move it
Change the text
Now, the hard parts are steps 2 and 3.
For step 2, you have to calculate the length of the new text. This is tricky because there are no built-in functions to tell you how wide text will be with a given set of styles. You pretty much have to create a duplicate element and measure it instead.
For step 3, you have to move the element without causing a jump before or after the text changes. My way of doing this is to use position: absolute and set left to the current position (thus eliminating any jerking there). I then transition to the correct position using transform (doing a little math to account for the current position), for performance. At the end of the transition, take away the style attribute and change the text.
One other thing to watch out for is the text jumping around when the image becomes position: absolute. For simplicity, I put the entire line in a display: flex container. If you don't want to use flex, you can use inline-block or block on the text and adjust the padding/height so it will keep the proper amount of space.
Here's what I came up with (also on JSFiddle):
var $img = document.getElementById('user');
var $text = document.getElementById('textToChange');
var $estimator = document.getElementById('estimator');
var extraWidth = $img.offsetLeft - $text.offsetWidth;
function estimate(text) {
$estimator.textContent = text;
var width = $estimator.offsetWidth;
$estimator.textContent = '';
return width;
}
document.getElementById('change-text')
.addEventListener('click', function() {
var newText = randomText();
var left = $img.offsetLeft;
$img.style.position = 'absolute';
$img.style.left = left + 'px';
$img.style.transition = 'transform linear 1s';
$img.style.transform = 'translateX(0)';
window.requestAnimationFrame(function() {
$img.style.transform = 'translateX(' + (extraWidth + estimate(newText) - left) + 'px)';
window.setTimeout(function() {
$text.textContent = newText;
$img.removeAttribute('style');
}, 1000);
});
});
// For testing
function randomText() {
var length = Math.floor(Math.random() * 43) + 3;
return 'Lorem ipsum dolor sit amet portris noc tefweep'.slice(0, length);
}
h2 {
position: relative;
height: 100px;
display: flex;
align-items: flex-end;
}
/* For measuring text width. I don't want it to be seen. */
.not-shown {
visibility: hidden;
color: transparent;
position: absolute;
z-index: -1;
}
<h2>
<span id="textToChange">text here</span>
<img id="user" src="http://placehold.it/100x100" alt="img">
</h2>
<h2 class="not-shown"><span id="estimator"></span></h2>
<button id="change-text">Change text</button>
Note that this does not work well if the text goes to multiple lines. I chose not to worry about that scenario.
I'm looking for a way in jQuery or pure JS to get the amount of pixels scrolled, not from the top of the page, but from the bottom of a div.
In other words I need to turn the amount scrolled beyond a div's height + its pixel distance from the top of the page into a variable.
I want to append this parallax code below so instead of calculating from the top of the page, calculates from a target div's distance from the top + its height.
/* Parallax Once Threshold is Reached */
var triggerOne = $('#trigger-01').offset().top;
$(window).scroll(function(e){
if ($(window).scrollTop() >= triggerOne) {
function parallaxTriggerOne(){
var scrolled = $(window).scrollTop();
$('#test').css('top',+(scrolled*0.2)+'px');
}
parallaxTriggerOne();
} else {
$('#test').css('top','initial');
}
});
I realize I didn't phrase this quite clear enough, I'm looking to only get the value of the amount of pixels scrolled since passing a div, so for example if I had a 200px tall div at the very top of the page and I scrolled 20 pixels beyond it, that variable I need would equal 20, not 220.
You can get a div's position by using div.offsetTop,
adding div.offsetHeight into div's distance from top of page will give you bottom of div, then you can subtract from window's scroll to get your desired value.
Feel free to ask if you have any doubts.
var div = document.getElementById('foo');
let div_bottom = div.offsetTop + div.offsetHeight;
var doc = document.documentElement;
var left = (window.pageXOffset || doc.scrollLeft) - (doc.clientLeft || 0);
var scroll_top, scroll_after_div;
setInterval(function(){
scroll_top = (window.pageYOffset || doc.scrollTop) - (doc.clientTop || 0);
scroll_after_div = scroll_top - div_bottom;
console.log(scroll_after_div);
}, 1000);
body { margin: 0; }
<div id="foo" style="position:relative; top: 100px; height: 30px; width: 100%; background-color: #000;"></div>
<div id="bar" style="position:relative; top: 700px; height: 30px; width: 100%; background-color: #000;"></div>
In this snippet setInterval method is printing the scroll value each second, you can scroll and see the change in value.
To work out the distance from the top of the page to the bottom of an element, you can add an elements outerHeight() with its offset().top.
Example: https://jsfiddle.net/dw2jwLpw/
console.log(
$('.target').outerHeight() + $('.target').offset().top
);
In pure JS you can get the bottom of the div directly with document.getElementById("my-element").getBoundingClientRect().bottom.
In jQuery you can use $('#my-element').offset().top + $('#my-element').height()
I am looking for a way to zoom into a div element. Since this question did not provide some code example, I decided to post the following.
This jsfiddle already helped, but as you can see in my adapted jsfiddle, the whole div scales. I just want the image inside to scale. the div should have an overflow if zoomed in (also scroll bars).
Is this possible without including other scripts e.g. panzoom?
HTML
<div id="pane">
<img src="http://i.stack.imgur.com/oURrw.png">
</div>
JavaScript
$('#pane').bind('mousewheel DOMMouseScroll', function(e){
var stage = $(this);
scaleData = getZoom(stage);
if ( e.originalEvent.detail < 0 ){
setZoom( scaleData.curScale * '.9', stage );
}
else{
setZoom( scaleData.curScale * '1.1', stage );
}
});
function setZoom(scale, el){
scale = Math.round(scale*10)/10;
el.attr({
style:
'zoom: '+scale+';'+
'-webkit-transform: scale('+scale+');'+
'-moz-transform: scale('+scale+');'+
'-o-transform: scale('+scale+');'+
'-ms-transform: scale('+scale+');'+
'transform: scale('+scale+');'
});
}
function getZoom(el){
var curZoom = el.css('zoom');
var curScale = el.css('transform') ||
el.css('-webkit-transform') ||
el.css('-moz-transform') ||
el.css('-o-transform') ||
el.css('-ms-transform');
if ( curScale === 'none' ){
curScale = 1;
}else{
//Parse retarded matrix string into array of values
var scaleArray = $.parseJSON(curScale.replace(/^\w+\(/,"[").replace(/\)$/,"]"));
//We only need one of the two scaling components as we are always scaling evenly across both axes
curScale = scaleArray[0];
}
return { curZoom: curZoom, curScale: curScale };
}
CSS
div#pane{
height: 20em;
margin: auto;
background-color: #ffffff;
overflow: scroll;
position: relative;
z-index: 0;
}
Thank you
If I understand correctly the solution is to change the 2nd line of the JS you provided in a JSFiddle to:
var stage = $(this).find('img');
I just included .find('img') to the end of what you had there. Previously you were zooming the entire div, now it zooms just the img tag.
Let's say I have a single HTML page. 2000 pixels long for example. I want to detect if a visitor reaches a certain point on the page.
The page structure:
0px = begin of the page;
500px = about us page;
1000px = contactpage;
Is there a way with jQuery to detect if a user reaches the points described above?
You probably want jQuery's scroll event-binding function.
Yes, I would create three divs and then have a mouse over event on each. Example:
$("#begin").mouseover(function(){
alert("over begin");
});
$("#about").mouseover(function(){
alert("over about");
});
$("#contact").mouseover(function(){
alert("over contact");
});
You can see a working fiddle here: http://jsfiddle.net/ezj9F/
Try THIS working snippet.
Using this code you don't have to know position of the element you want to check if it is visible.
JQuery
var $window = $(window);
// # of pixels from the top of the document to the top of div.content
var contentTop = $("div.content").offset().top;
// content is visible when it is on the bottom of the window and not at the top
var contentStart = contentTop - $window.height();
// content is still visible if any part of his height is visible
var contentEnd = contentTop + $("div.content").height();
$window.scroll(function() {
var scrollTop = $window.scrollTop();
if(scrollTop > contentStart && scrollTop < contentEnd) {
console.log('You can see "HELLO"!');
} else {
console.log('You cannot see "HELLO"!');
}
});
HTML
<div class="scroll"></div>
<div class="content">HELLO</div>
<div class="scroll"></div>
CSS
div.scroll {
background-color: #eee;
width: 100px;
height: 1000px;
}
div.content {
background-color: #bada55;
width: 100px;
height: 200px;
}
EDIT: Now the algorithm is checking if any part of the div.content is visible (it is considering height of the element). If you are not interested in that change contentEnd to var contentEnd = contentTop.