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sgpinkus/both-dirs-try.html

Last active August 14, 2020 12:11
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Example of how "infinite scroll" works out of the box.
Raw
both-dirs-try.html
<!DOCTYPE html>
<html>
<head>
<title>Simplified Infinite Scroll</title>
<meta charset="utf-8" />
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js"></script>
<style type='text/css'>
* { border: 0; padding: 0; margin: 0; box-sizing: border-box; }
html, body { height: 100%; }
body { display: flex; flex-flow: column wrap; }
header, footer { background-color: #888; max-height: 40px; min-height: 40px; flex: 1 }
header, footer { text-align: center; }
#message-scroll-container {
flex: 1;
margin: 0 auto;
border: solid 1px #000;
width: 400px;
overflow-y: scroll;
}
#message-container { min-height: 101%; }
.message-block { border: solid 1px #000; }
.loader { position: fixed; left: 50%; top: 50%; transform: translate(-50%, -50%); visibility: hidden; }
</style>
<script>
let bounds = { top: 0, bottom: 0 };
let messageId = 0;
jQuery(document).ready(function() {
console.log("Ready");
addMessages(5);
bounds['bottom'] = 5;
let scrollContainer = jQuery('#message-scroll-container')
scrollContainer.scrollTop = scrollContainer.scrollTopMax / 2;
scrollContainer.on('scroll', scrollHandler);
})
function scrollHandler(e, f) {
console.log(this.scrollTop, this.scrollTopMax);
let edge = undefined;
if(this.scrollTop === this.scrollTopMax) {
edge = 'bottom';
}
else if(this.scrollTop === 0) {
edge = 'top';
}
if(edge) {
let scrollTopMax = this.scrollTopMax
console.log(`Scoll is at ${edge}. Loading more.`)
new Promise(resolve => {
jQuery('.loader').css('visibility', 'visible');
setTimeout(() => {
if(bounds[edge] < 15) {
addMessages(5, edge);
bounds[edge] += 5;
diff = this.scrollTopMax - scrollTopMax;
this.scrollTop += (edge === 'bottom' ? 0 : diff);
}
else {
console.log('No more messages');
this.scrollTop += (edge === 'bottom' ? -20 : 20);
}
resolve();
}, 700);
})
.finally(() => jQuery('.loader').css('visibility', 'hidden'));
}
}
function addMessages(n = 2, edge = 'bottom') {
let messages = jQuery('#message-scroll-container > div');
for(let i = 1; i <= n; i++) {
id = (bounds[edge] + i) * (edge === 'bottom' ? 1 : -1);
let message = `<div class="message-block"><p><strong>${id}</strong>&nbsp; "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."</p><br /></div>`;
if(edge === 'bottom') {
messages.append(message);
} else if(edge === 'top') {
messages.prepend(message);
}
}
}
</script>
</head>
<body>
<img class='loader', src='data:image/png;base64,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' alt='Loading...'>
<header>
<p>Header</p>
</header>
<div id='message-scroll-container'>
<h2>Messages</h2>
<div id='message-container'></div>
</div>
<footer>
<p>Footer</p>
</footer>
</body>
</html>
Raw
index.html
<!DOCTYPE html>
<html>
<head>
<title>Simplified Infinite Scroll</title>
<meta charset="utf-8" />
<script src="https://code.jquery.com/jquery-3.5.1.slim.min.js"></script>
<style type='text/css'>
* { border: 0; padding: 0; margin: 0; box-sizing: border-box; }
html, body { height: 100%; }
body { display: flex; flex-flow: column wrap; }
header, footer { background-color: #888; max-height: 40px; min-height: 40px; flex: 1 }
header, footer { text-align: center; }
#message-scroll-container {
flex: 1;
margin: 0 auto;
border: solid 1px #000;
width: 400px;
overflow-y: scroll;
}
#message-container { min-height: 101%; }
.message-block { border: solid 1px #000; }
.loader { position: fixed; left: 50%; top: 50%; transform: translate(-50%, -50%); visibility: hidden; }
</style>
<script>
jQuery(document).ready(function() {
console.log("Ready");
addMessages(1);
jQuery('#message-scroll-container')[0].scrollTop = 0;
jQuery('#message-scroll-container').on('scroll', scrollHandler );
})
function scrollHandler(e, f) {
console.log(this.scrollTop, this.scrollTopMax);
if(this.scrollTop === this.scrollTopMax) {
const messageCount = jQuery('.message-block').length;
console.log(`${messageCount} of 15`);
new Promise(resolve => {
jQuery('.loader').css('visibility', 'visible');
setTimeout(() => {
if(messageCount > 15) this.scrollTop -= 20;
else addMessages(5);
resolve();
}, 700);
})
.finally(() => jQuery('.loader').css('visibility', 'hidden'));
}
}
function addMessages(n = 2) {
for(let i = 0; i < n; i++) {
jQuery('#message-scroll-container > div').append(`<div class="message-block"><p><strong></strong>&nbsp; "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum."</p><br />
</div>`);
}
}
</script>
</head>
<body>
<img class='loader', src='data:image/png;base64,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' alt='Loading...'>
<header>
<p>Header</p>
</header>
<div id='message-scroll-container'>
<h2>Messages</h2>
<div id='message-container'></div>
</div>
<footer>
<p>Footer</p>
</footer>
</body>
</html>
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