scrollama
Version:
Lightweight scrollytelling library using IntersectionObserver
241 lines (238 loc) • 6.61 kB
HTML
<html>
<head>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<title>Scrollama Demo: Basic</title>
<meta
name="description"
content="Scrollama Demo: Error when steps are children of multiple scrollable elements"
/>
<meta name="viewport" content="width=device-width, initial-scale=1" />
<style>
/* default / demo page */
* {
box-sizing: border-box;
}
html,
body {
margin: 0;
padding: 0;
font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
Oxygen, Ubuntu, Cantarell, "Open Sans", "Helvetica Neue", sans-serif;
}
body {
font-weight: 300;
color: #2a2a2a;
height: 100vh;
}
main {
/* NO OVERFLOW HERE */
}
p,
h1,
h2,
h3,
h4,
a {
margin: 0;
font-weight: 300;
}
a,
a:visited,
a:hover {
color: #f30;
text-decoration: none;
border-bottom: 1px solid currentColor;
}
#intro {
max-width: 40rem;
margin: 1rem auto;
text-align: center;
}
.intro__overline {
font-size: 1.4rem;
}
.intro__hed {
font-size: 1.4rem;
margin: 1.5rem auto;
text-transform: uppercase;
font-weight: 900;
letter-spacing: 0.05em;
}
.intro__dek {
font-size: 1.4rem;
margin-bottom: 1rem;
}
/* demo */
#bottom-spacer {
height: 100vh;
}
/* scrollama */
#step-container-element {
position: relative;
height: 500px;
width: 50vw;
overflow-y: scroll;
}
.scroll__text {
position: relative;
padding: 0 1rem;
margin: 0 auto;
width: 33%;
}
.step {
margin: 2rem auto 4rem auto;
border: 1px solid #333;
background-color: #fff;
}
.step.is-active {
background-color: lightgoldenrodyellow;
}
.step p {
text-align: center;
padding: 1rem;
font-size: 1.5rem;
}
.section_title {
position: sticky;
top: 0;
}
nav {
position: fixed;
top: 0;
left: 0;
z-index: 1000;
background: white;
padding: 1rem;
}
</style>
</head>
<body>
<main>
<section id="intro">
<p class="intro__overline">
<a href="https://github.com/russellgoldenberg/scrollama"
>scrollama.js</a
>
</p>
<h1 class="intro__hed">
Scrollama throws an error when steps are children of a scrollable
element
</h1>
<p class="intro__dek">
Calculating the scroll direction is problematic when steps are
children of a scrollable element that isn't the page scroll. This page
provides an example of what not to do:
<strong>do NOT place steps inside a scrollable element</strong> with
<em>overflowY: scroll</em> or <em>overflowY: auto</em> and fixed
height.
</p>
<p class="intro__dek">To demonstrate the incorrect behavior:</p>
<ul class="intro__dek">
<li>
ensure that the olive-colored element intersects the trigger (the
dotted line)
</li>
<li>move the mouse pointer inside the olive-colored element</li>
<li>
scroll up and down with the mouse pointer inside the colored
container. You may have to scroll up and down several times before
the direction calculation becomes incorrect
</li>
</ul>
<p class="intro__dek">
<strong
>Notice that step events are not triggered correctly when the inner
container scrolls without the window element scrolling.</strong
>
</p>
</section>
</main>
<script src="./d3.v4.min.js"></script>
<script src="https://unpkg.com/intersection-observer"></script>
<script src="../build/scrollama.js"></script>
<script>
function buildSection(
title,
parentSelector,
sectionId,
nSteps,
stepHeight,
background
) {
var scroll = d3
.select(parentSelector)
.append("section")
.append("div")
.classed("scroll__text", true)
.attr("id", sectionId)
.style("background", background);
scroll
.append("div")
.append("h2")
.classed("section_title", true)
.html(title);
var data = d3.range(nSteps);
scroll
.selectAll("div.step")
.data(data)
.enter()
.append("div")
.classed("step", true)
.attr("data-step", function(datum) {
return datum.toString();
})
.style("height", stepHeight + "px")
.append("p")
.html(function(datum) {
return "STEP " + datum;
});
return scroll.node();
}
function buildScroller(sectionId) {
var scroller = scrollama()
.setup({
step: "#" + sectionId + " .step",
debug: true,
offset: 0.9,
progress: true
})
.onStepEnter(function handleStepEnter(response) {
console.log(response.index, "-------- enter");
response.element.classList.add("is-active");
})
.onStepExit(function handleStepExit(response) {
console.log(response.index, "-------- exit");
response.element.classList.remove("is-active");
})
.onStepProgress(function handleStepProgress(response) {
console.log(
response.index,
"-------- progress -",
response.progress
);
});
// setup resize event
window.addEventListener("resize", scroller.resize);
}
function init() {
var scrollableStepContainerId = "step-container-element";
buildSection(
"I'm a scrollable element containing steps",
"main",
scrollableStepContainerId,
5,
150,
"olive"
);
buildScroller(scrollableStepContainerId);
d3.select("main")
.append("div")
.attr("id", "bottom-spacer");
}
// kick things off
init();
</script>
</body>
</html>