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Scroll a web page using Javascript whose scroll triggers at the middle of page

I have encountered some websites which has footer at the bottom and scroll actually happens when I scroll to the area above footer.
To automatically scroll those pages, but the problem with my code currently is it goes at the bottom of the page, where I directly reach footer and hence the scroll trigger which is present just above the footer does not gets triggered.
Is there any way to achieve the same?
This is what I have tried currently which I am executing from the console:
(function() {
var intervalObj = null;
var retry = 0;
var clickHandler = function() {
console.log("Clicked; stopping autoscroll");
clearInterval(intervalObj);
document.body.removeEventListener("click", clickHandler);
}
function scrollDown() {
var scrollHeight = document.body.scrollHeight,
scrollTop = document.body.scrollTop,
innerHeight = window.innerHeight,
difference = (scrollHeight - scrollTop) - innerHeight
if (difference > 0) {
window.scrollBy(0, difference);
if (retry > 0) {
retry = 0;
}
console.log("scrolling down more");
} else {
if (retry >= 3) {
console.log("reached bottom of page; stopping");
clearInterval(intervalObj);
document.body.removeEventListener("click", clickHandler);
} else {
console.log("[apparenty] hit bottom of page; retrying: " + (retry + 1));
retry++;
}
}
}
document.body.addEventListener("click", clickHandler);
intervalObj = setInterval(scrollDown, 1000);
})()
There are many websites that has this feature, to test the same one of the website which you can try is
https://www.zomato.com/bangalore/indiranagar-restaurants
Note : The question similar to this does not answer how to scroll at some mid point of page instead it takes me directly to the footer, so this is not a duplicate

Logic is to retain to the middle of the Scroller unless the page is completely loaded. We can tweak the code a little to achieve the last position of scroller. Try this:
var scrollHeight = 0,
newScrollHeight;
do {
window.scrollTo(0, document.body.scrollHeight / 2);
newScrollHeight = document.body.scrollHeight / 2;
if (newScrollHeight == scrollHeight) {
break;
} else {
scrollHeight = newScrollHeight;
}
} while (true);

Although Kumar Rishabh has already answered your question, I have another solution for this situation.
Set the domain to detect if the user scrolls to the domain.
The effect just like the website you povider . https://www.zomato.com/bangalore/indiranagar-restaurants
I do some simple example for you with pure Javascript.
Fragment core code:
// Here is domain to detect if user scroll into.
if (
triggerDomain.getBoundingClientRect().top < window.innerHeight &&
triggerDomain.getBoundingClientRect().bottom > 0
) {
if (getMore === false) {
getMore = true
// Do something you want here ....
console.info('got more !!')
Full code sample, check code snippet:
const rootElement = document.getElementById("rootDiv");
const triggerDomain = document.getElementById("triggerDomain");
let getMore = false;
function detectScrollIntoDomain() {
// Here is domain to detect if user scroll into.
if (
triggerDomain.getBoundingClientRect().top < window.innerHeight &&
triggerDomain.getBoundingClientRect().bottom > 0
) {
if (getMore === false) {
getMore = true;
// Do something you want here ....
console.info("got more !!");
setTimeout(() => {
let currentScrollTop = rootElement.scrollTop;
for (let i = 0; i < 15; i++) {
let r = Math.floor(Math.random() * 255);
let g = Math.floor(Math.random() * 255);
let b = Math.floor(Math.random() * 255);
const contentElement = document.getElementById("content");
const card = document.createElement("div");
card.className = "contentCard";
card.style.backgroundColor = `rgba(${r}, ${g}, ${b})`;
contentElement.appendChild(card);
}
rootElement.scrollTo(0, currentScrollTop);
// Don't forget to set flag to `false`.
getMore = false;
}, 200);
}
}
}
rootElement.addEventListener("scroll", detectScrollIntoDomain, {
passive: true
});
html,
body {
position: relative;
font-family: sans-serif;
padding: 0;
margin: 0;
height: 100%;
width: 100%;
}
h1,
h2 {
margin: 0;
color: aliceblue;
}
#rootDiv {
position: relative;
overflow: auto;
height: 100%;
width: 100%;
}
#header {
height: 200px;
background-color: rgb(112, 112, 112);
}
#content {
display: flex;
flex-wrap: wrap;
position: relative;
height: fit-content;
background-color: rgb(136, 136, 136);
}
#content div:first-child {
height: 600px;
width: 100%;
display: flex;
flex-direction: column;
justify-content: center;
align-items: center;
}
#triggerDomain {
position: absolute;
bottom: 0px;
outline: 1px dashed rgb(3, 25, 119);
height: 500px;
width: 100%;
background: repeating-linear-gradient(
135deg,
rgba(46, 45, 45, 0.3) 0,
rgba(46, 45, 45, 0.3) 10px,
rgba(136, 136, 136, 0.3) 10px,
rgba(136, 136, 136, 0.3) 20px
);
}
#footer {
height: 180%;
background-color: rgb(112, 112, 112);
}
.contentCard {
width: 180px;
height: 180px;
margin: 12px;
border-radius: 8px;
background-color: aquamarine;
}
<!DOCTYPE html>
<html>
<head>
<title>Parcel Sandbox</title>
<meta charset="UTF-8" />
<link rel="stylesheet" type="text/css" href="./src/styles.css"
</head>
<body>
<div id="rootDiv">
<div id="header">
<h1>Header</h1>
</div>
<div id="content">
<div>
<h2>Content</h2>
<h2>Scroll down to get more cards.</h2>
</div>
<div id="triggerDomain">
<h2>Trigger domain</h2>
</div>
</div>
<div id="footer">
<h2>Footer</h2>
</div>
</div>
<script src="src/index.js"></script>
</body>
</html>
Hope to help you !

JavaScript moving text animation doesn't work. FULL CODE

JS: My problem is in running the following JS script, it's supposed to be very easy ,i think, but i can't understand why won't it run. I've just started coding and i'm already stuck in this problem. I want the text to go up (by increasing the bottom in CSS) for 5px until it reaches pos=6 ; then clearInterval should do its job.
CSS: I've put the position of div's to RELATIVE as i've read in some tutorials but didn't put the " container's " position to ABSOLUTE, may it be the problem?
<html>
<head>
<style>
html {
height: 100%;
}
body {
height: ;
width: 100%;
background-color: ;
margin: 0px;
padding: 0px;
}
#generale {
height: 100%;
width: 100%;
}
#intestazione {
height: 7%;
width: 100%;
float: left;
background-image: url(immagini/sfumatura.png);
position: static;
}
#profilo {
position: static;
float: right;
width: 12%;
height: 100%;
}
.testo_rialzato {
position: relative;
float: right;
width: auto;
height: 100%;
padding-left: 20px;
padding-right: 20px;
background-color: transparent;
}
</style>
</head>
<body>
<div id="generale">
<div id="intestazione">
<div id="profilo"></div>
<div class="testo_rialzato sumba">
<p>Sp</p>
</div>
<div class="testo_rialzato ap">
<p>App</p>
</div>
<div class="testo_rialzato te">
<p>Te</p>
</div>
<div class="testo_rialzato do">
<p>Dom</p>
</div>
<div class="testo_rialzato big">
<p style="line-height:70%; margin-top:8px; text-align:center;">Big</p>
</div>
</div>
<script>
var ez = document.querySelectorAll(".sumba , .ap , .te , .do, .big");
ez.onmouseover = alza();
var intervallo = setInterval(alza, 100);
function alza() {
var pos = 0;
if (pos = 6) {
clearInterval(intervallo);
} else {
ez.style.bottom = pos + "px";
}
}
</script>
</div>
</body>
</html>

First thing is , why declaring you are using event on an array of dome node (result of querySelectorAll will return array of domenodes ) so in order to attach mouseover and also apply some style you have to loop around those nodes .
Seconde thing while declaring set interval, its usless to use mousemovehere ?
Also the condition if is wrong you're using assignment , so you have to use == or === in order to make comaparison .
See below snippet :
var ez = document.querySelectorAll(".sumba , .ap , .te , .do, .big");
var pos = 0;
var intervallo = setInterval(alza, 100);
ez.forEach(function(el){
el.addEventListener("mouseover", alza);
})
function alza() {
if (pos == 25) {
clearInterval(intervallo);
} else {
ez.forEach(function(el){
el.style.bottom = pos + "px";
});
pos++;
}
}
.sumba, .ap {
position:absolute;
}
.ap {
color:red;
left:40px
}
<!-- begin snippet: js hide: false console: true babel: false -->
<div class="sumba">Text</div>
<div class="ap">Text 2</div>

try this
<!DOCTYPE html>
<html>
<style>
#container {
width: 400px;
height: 400px;
position: relative;
}
#animate {
width: 50px;
height: 50px;
position: absolute;
}
</style>
<body>
<p>
<button onclick="myMove()">Click Me</button>
</p>
<div id ="container">
<div id ="animate">ggg</div>
</div>
<script>
function myMove() {
var elem = document.getElementById("animate");
var pos = 0;
var id = setInterval(frame, 5);
function frame() {
if (pos == 350) {
clearInterval(id);
} else {
pos++;
elem.style.left = pos + 'px';
}
}
}
</script>
</body>
</html>

Function to count number of line breaks acts differently on $(window).on('resize') and $(document).ready

I have a function which counts the number of line breaks in a div, depending on the width of the window. While the functions works fine when placed in the $(window).on('resize') function, it does not work when put in $(document).ready() function. I want it to work right on page load, and also window resize, how do I support both?
JSFiddle
Javascript/jQuery:
// functions called in both document.ready() and window.resize
$(document).ready(function(){
var lineCount = getLineCount();
postItems(lineCount);
$('.answer').text("Ready");
});
$(window).on('resize', function(){
var lineCount = getLineCount();
postItems(lineCount);
$('.answer').text("Number of lines: " + lineCount);
});
// calculates the amount of lines required to hold the items
function getLineCount() {
var lineWidth = $('.line').width();
var itemWidthSum = 0;
var lineCount=1;
$('.item').each(function(index, element) {
if((lineWidth - itemWidthSum) > ($(element).outerWidth())) {
itemWidthSum = itemWidthSum + $(element).outerWidth();
} else {
lineCount++;
itemWidthSum = $(element).outerWidth();
}
});
return lineCount;
}
// overlays rows for the amount of linebreaks
function postItems(lineCount){
var container = $('<div />');;
for(var i = 1; i <= lineCount; i++) {
container.append('<div class="line">' + i + '</div>');
}
$('.line-wrap').html(container);
}
You'll see at the start of the page, it incorrectly shows 17 lines, and then once you resize it will show the correct amount.

The issue lies in the first line of getLineCount(). Originally you had
var lineWidth = $('.line').width();
but no elements with the class "line" exist yet on your page (since they get added in your postItems() method. I changed it to
var lineWidth = $(".container").width();
instead, and now your code should be working. Snippet posted below:
$(document).ready(function(){
var lineCount = getLineCount();
postItems(lineCount);
$('.answer').text("Ready");
});
$(window).on('resize', function(){
var lineCount = getLineCount();
postItems(lineCount);
$('.answer').text("Number of lines: " + lineCount);
});
// calculates the amount of lines required to hold the items
function getLineCount() {
var lineWidth = $('.container').width();
var itemWidthSum = 0;
var lineCount=1;
$('.item').each(function(index, element) {
if((lineWidth - itemWidthSum) > ($(element).outerWidth())) {
itemWidthSum = itemWidthSum + $(element).outerWidth();
} else {
lineCount++;
itemWidthSum = $(element).outerWidth();
}
});
return lineCount;
}
// overlays rows for the amount of linebreaks
function postItems(lineCount){
var container = $('<div />');;
for(var i = 1; i <= lineCount; i++) {
container.append('<div class="line">' + i + '</div>');
}
$('.line-wrap').html(container);
}
body {
text-align:center;
}
.answer {
position: fixed;
left: 0;
bottom: 0;
}
.container {
position: relative;
width: 50%;
margin: 0 auto;
border: 1px solid #e8e8e8;
display: inline-block;
}
.item {
height: 50px;
padding:0 10px;
background-color: #aef2bd;
float: left;
opacity:0.2;
white-space: nowrap;
}
.line-wrap {
position: absolute;
border: 1px solid red;
width: 100%;
height: 100%;
top:0; left: 0;
}
.line {
height: 50px;
width: 100%;
background-color: blue;
opacity:0.5;
color: white;
transition: all 0.5s ease;
}
.line:hover {
background-color: yellow;
color: #000;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="container">
<div class="item-wrap">
<div class="item">Computer Science</div>
<div class="item">Language</div>
<div class="item">Marketing</div>
<div class="item">Biology</div>
<div class="item">Computer Science</div>
<div class="item">Language</div>
<div class="item">Marketing</div>
<div class="item">Biology</div>
<div class="item">Computer Science</div>
<div class="item">Language</div>
<div class="item">Marketing</div>
<div class="item">Biology</div>
<div class="item">Computer Science</div>
<div class="item">Language</div>
<div class="item">Marketing</div>
<div class="item">Biology</div>
</div>
<div class="line-wrap">
</div>
</div>
<h1 class="answer"></h1>

Programatically resize the H div and C div along with the resizer

When I click-drag (#cssNav) to the right, it is not moving proportionately along with the #html and #css div.
This might be something very obvious, but still am not able to figure it out, what am I missing here, please help?
Note: I don't want to use display:flex
codepen
$("#htmlNav").on("mousedown", dragStartH);
$("#cssNav").on("mousedown", dragStartH);
$("#jsNav").on("mousedown", dragStartH);
function dragStartH(e) {
e.preventDefault();
dragMeta = {};
dragMeta.pageX0 = e.pageX;
dragMeta.elem = this;
dragMeta.offset0 = $(this).offset();
dragMeta.codeWindow = "#" + $(e.target).attr("id").replace("Nav", "");
function handle_dragging(e) {
var change = e.pageX - dragMeta.pageX0;
var left = dragMeta.offset0.left + change;
$(dragMeta.elem).offset({ left: left });
$("#css").width($("#css").width() - change + "px");
$("#html").width($("#html").width() + change + "px");
}
function handle_mouseup(e) {
$("body")
.off("mousemove", handle_dragging)
.off("mouseup", handle_mouseup);
}
$("body").on("mouseup", handle_mouseup).on("mousemove", handle_dragging);
}
$(document).ready(function() {
var widthPercent = ($(window).width() - 30) / 3;
$("#html").width(widthPercent + "px");
$("#css").width(widthPercent + "px");
$("#js").width(widthPercent + "px");
});
html, body {
height: 100%;
margin: 0;
}
.container{
width:100%;
height: 100%;
background-color:#343;
display: flex;
flex-direction: column;
color: #fff;
margin: 0;
}
#preview, #code{
background-color:#433;
height: 50%;
width: 100%;
margin: 0;
}
#code{
border-bottom: #333 solid 2px;
width: 100%
}
#previewNav, #codeNav{
background-color:#bbb;
height: 10px;
width: 100%;
cursor: row-resize;
}
#html{
background-color: #BFB;
}
#css{
background-color: #FBB;
}
#js{
background-color: #BBF;
}
#html, #css, #js{
float: left;
width: 32%;
height: 100%;
}
#htmlNav, #cssNav, #jsNav{
background-color:#bbb;
float: left;
height:100%;
width: 10px;
cursor: col-resize;
z-index:10;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="container">
<div id="codeNav"></div>
<div id="code">
<div id="htmlNav"></div>
<div id="html">H</div>
<div id="cssNav"></div>
<div id="css">C</div>
<div id="jsNav"></div>
<div id="js">J</div>
</div>
<div id="previewNav"></div>
<div id="preview">P</div>
</div>

This is how I would do it:
Keep track of which handle you press with navTypeand check if the user is holding its mouse down with dragging.
Then when the user moves the mouse in the document and it is holding its mouse down (dragging) it will move the #html, #css and #js accordingly
Change your javascript into this:
var mouseX, prevMouseX, navType, change;
var dragging = false;
$("#cssNav").mousedown(function () {
dragging = true;
navType = "css";
});
$("#jsNav").mousedown(function () {
dragging = true;
navType = "js";
});
$(document).mousemove(function (e) {
mouseX = e.pageX;
if(dragging){
e.preventDefault();
change = mouseX - prevMouseX;
if(navType == "css" && ($("#css").width() - (change)) > 0 && ($("#html").width() + (change)) > 0){
var hw = $("#html").width();
var cw = $("#css").width();
$("#html").width(hw + change);
$("#css").width(cw - change);
} else if(navType == "js" && ($("#css").width() + (change)) > 0 && ($("#js").width() - (change)) > 0){
var cw = $("#css").width();
var jw = $("#js").width();
$("#css").width(cw + change);
$("#js").width(jw - change);
}
}
prevMouseX = mouseX;
}).mouseup(function () {
dragging = false;
}).mouseleave(function () {
dragging = false;
});

How can I add limits to a custom scrolling element?

I have a pretty huge image being displayed in a container, the image stretches with the view port as it gets resized, but as the image is so big I have added scroller buttons to the side of the page, up and down, the only problem I have now is that when I press up or down there is no limit, the user can keep going until the image is completely out of sight, how can I stop that from happening?
Here is the code I have thus far,
HTML:
<body>
<div id="wrapper">
<div class="scroll top"></div>
<div id="content">
<div id="zoom_container">
<img id="image" src="8052x2000px" />
</div>
</div>
<div class="scroll bot"></div>
</div>
</body>
CSS:
body {
width: 100%;
height: 100%;
margin: 0;
padding: 0;
}
#wrapper {
overflow: hidden;
height: 100%;
max-height: 100%;
}
#content {
min-height: 100% !important;
height: 100%;
width: 100%;
margin: 0;
padding: 0;
}
#image {
position: fixed;
top: 0;
left: 0;
width: 100%;
}
jQuery:
//side scroller bar
$('.scroll').live('click', function(){
var direction = $(this).hasClass('top');
var img_pos_top = $("#zoom_container img").position().top;
var inc = 0;
inc = $("#zoom_container img").height() / 10;
if(direction)
{
inc = $("#zoom_container img").position().top + inc;
}
else
{
inc = $("#zoom_container img").position().top - inc;
}
$("#zoom_container img").css({ position: 'relative',top: inc });
});
so as you can see I am incrementing or decrementing the top positioning of the image by 10% of it's height each click, how can I make sure the top of the image will never go further down than the top of the viewport and the bottom of the image never further up than the bottom of the viewport?
Is there a better more efficient way of achieving the same result?

Have a try this one.
<html>
<head>
<title>Canvas Sizing</title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.0/jquery.min.js"></script>
<script type="text/javascript">
$(function() {
var canvasContext;
resizeCanvas();
$(window).resize(function() { resizeCanvas() });
function resizeCanvas()
{
var w = window.innerWidth - 40;
var h = window.innerHeight - 40;
var canvasString = '<canvas id="mainCanvas" width="' + w + '" height="' + h + '">Canvas is not supported</canvas>';
$('#contentholder').empty();
$(canvasString).appendTo('#contentholder');
canvasContext = $('#mainCanvas').get(0).getContext('2d');
drawOnCanvas();
}
function drawOnCanvas()
{
var x = 15;
var y = 35;
canvasContext.font = "30pt serif";
canvasContext.fillStyle="#0f0";
canvasContext.fillText("Hello World!", x, y);
}
});
</script>
<style>
#mainCanvas
{
background-color: #000;
border: solid 3px #0F0;
}
body
{
background: #000;
}
#contentholder
{
width: 99%;
height: 99%;
margin: auto;
}
</style
</head>
<body>
<div id="contentholder"></div>
</body>