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Recognize scroll as an action and observe relative movement #1

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Recognize scroll as an action and observe relative movement #1

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d3bc45e
Setup demo for scrollers
jeremyfelt Oct 24, 2024
32d50fe
Recognize `scroll` as an action and observe relative movement
jeremyfelt Oct 24, 2024
cf686ff
Add example animations on scrollers
jeremyfelt Oct 24, 2024
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2 changes: 1 addition & 1 deletion build/index.js
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30 changes: 28 additions & 2 deletions demo/css/style.css
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,11 @@ body {

.container {
position: relative;
padding: 100vh 0; /* Add padding to allow scrolling */
padding: 100vh 0 200vh 0; /* Add padding to allow scrolling */
}

.scrollers .container {
padding-top: 20vh;
}

.horizontal-line {
Expand Down Expand Up @@ -36,8 +40,13 @@ body {
position: relative;
}

.double-box {
height: 200px;
}

.demo-box::before,
.demo-box::after {
content: attr(class);
content: attr(style);
position: absolute;
bottom: -20px;
left: 0;
Expand All @@ -50,9 +59,26 @@ body {
background-color: rgba(255, 255, 255, 0.8);
padding: 2px;
border-radius: 3px;
width: fit-content;
}

.demo-box::after {
content: attr(class);
top: -20px;
bottom: initial;
}

.observe-triggered {
transform: scale(1.1);
box-shadow: 0 0 10px rgba(0,0,0,0.5);
}

.animated-left {
transform: translateX( calc( var( --distance-from-trigger ) * -1px ) );
transition: transform 50ms linear;
}

.animated-right {
transform: translateX( calc( var( --distance-from-trigger ) * 1px ) );
transition: transform 50ms linear;
}
46 changes: 46 additions & 0 deletions demo/scrollers.html
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Original file line number Diff line number Diff line change
@@ -0,0 +1,46 @@
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Observe Triggers Demo</title>
<link rel="stylesheet" href="../demo/css/style.css">
<link rel="stylesheet" href="../demo/css/animations.css">
<link rel="stylesheet" href="../demo/css/colors.css">
<style>
:root {
--distance-from-trigger: 0;
}
</style>
</head>
<body class="scrollers">
<div class="container">
<div class="horizontal-line" style="top: 10vh" data-percentage="10%"></div>
<div class="horizontal-line" style="top: 20vh" data-percentage="20%"></div>
<div class="horizontal-line" style="top: 30vh" data-percentage="30%"></div>
<div class="horizontal-line" style="top: 40vh" data-percentage="40%"></div>
<div class="horizontal-line" style="top: 50vh" data-percentage="50%"></div>
<div class="horizontal-line" style="top: 60vh" data-percentage="60%"></div>
<div class="horizontal-line" style="top: 70vh" data-percentage="70%"></div>
<div class="horizontal-line" style="top: 80vh" data-percentage="80%"></div>
<div class="horizontal-line" style="top: 90vh" data-percentage="90%"></div>

<div class="demo-box double-box observe-trigger-10-top-scroll observe-scroll animated-left" style="background-color: #ff5733;"></div>
<div style="height: 30vh;"></div> <!-- Spacer -->
<div class="demo-box observe-trigger-30-top-scroll observe-scroll animated-right" style="background-color: #33ff57;"></div>
<div style="height: 10vh;"></div> <!-- Spacer -->

</div>

<script type="module">
import ObserveTriggers from '../src/index.js';

new ObserveTriggers();

window.addEventListener('observerTriggered', (event) => {
const { element, isIntersecting, config } = event.detail;
console.log(`Element intersected at ${config.rootMargin}% of viewport ${config.edge}. Action: ${config.action}, Custom class: ${config.class}`);
});
</script>
</body>
</html>
89 changes: 87 additions & 2 deletions src/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,10 @@ class ObserveTriggers {
};
this.observers = new Map();
this.elementStates = new WeakMap();
this.scrollers = new Map();
this.scrollersActive = false;
this.handleScrollers = this.handleScrollers.bind(this);
this.viewportHeight = false;
this.init();
}

Expand All @@ -32,7 +36,7 @@ class ObserveTriggers {
* - baseTriggerClass: The base class name that triggers the observer.
* - rootMargin: The root margin for the observer.
* - edge: (Optional, default top) The edge to observe: top, bottom, left, right.
* - action: (Optional, default toggle) The action to perform: toggle, add, remove, replace.
* - action: (Optional, default toggle) The action to perform: toggle, add, remove, replace, scroll.
* - class: (Optional, default observe-triggered) The class to add, toggle, or remove.
* - root: (Optional, default null) The root element to observe.
*
Expand Down Expand Up @@ -76,7 +80,9 @@ class ObserveTriggers {

// Parse for a specified action, if it exists.
if (
['toggle', 'add', 'remove', 'replace'].includes(parts[currentPart])
['toggle', 'add', 'remove', 'replace', 'scroll'].includes(
parts[currentPart]
)
) {
config.action = parts[currentPart];
currentPart++;
Expand Down Expand Up @@ -162,6 +168,40 @@ class ObserveTriggers {
this.observers.get(element).set(className, observer, false);
}

/**
* Handle scrollers.
*
* @param {Event} scrollEvent The scroll event.
*/
handleScrollers(scrollEvent) {
if (!this.scrollers) {
return;
}

this.scrollers.forEach(({ classes, config }, element) => {
if (false === this.viewportHeight) {
this.viewportHeight = window.innerHeight;
}

// If `observe-scroll` is present, calculate the distance from the top of the viewport to the top of the scroller.
if (classes.includes('observe-scroll')) {
// Calculate the distance from the top of the viewport to the top of the scroller.
let hasScrolledAmount =
this.viewportHeight * (config.rootMargin / 100) -
element.getBoundingClientRect().top;

if (hasScrolledAmount < 0) {
hasScrolledAmount = 0;
}

element.style.setProperty(
'--distance-from-trigger',
hasScrolledAmount
);
}
});
}

/**
* Handle an observed intersection.
*
Expand Down Expand Up @@ -213,6 +253,51 @@ class ObserveTriggers {
}
});
element.classList.add(config.class);
break;
case 'scroll':
if (
entry.isIntersecting &&
!this.scrollers.has(element) &&
isTriggered
) {
const scrollerClasses = [];

// Capture any class names that start with `observe-scroll`.
element.classList.forEach((className) => {
if (className.startsWith('observe-scroll')) {
scrollerClasses.push(className);
}
});

// Add this scroller to the scrollers map.
this.scrollers.set(element, {
classes: scrollerClasses,
config,
});
} else if (
!entry.isIntersecting &&
this.scrollers.has(element)
) {
this.scrollers.delete(element);
}

// If there are intersecting scrollers, setup a scroll event listener.
if (this.scrollers.size > 0 && !this.scrollersActive) {
window.addEventListener(
'scroll',
this.handleScrollers,
{ passive: true }
);
this.scrollersActive = true;
} else if (this.scrollers.size === 0) {
window.removeEventListener(
'scroll',
this.handleScrollers,
{ passive: true }
);
this.scrollersActive = false;
}

break;
case 'toggle':
default:
Expand Down