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HTML
<main id="loading-zone" aria-busy="true">
<p>Loading Level</p>
<div class="card">
<label>
<span class="sr-only">Loading progress</span>
<progress
indeterminate
role="progressbar"
aria-describedby="loading-zone"
tabindex="-1"
>unknown</progress>
</label>
</div>
</main>
CSS
progress {
--_track: hsl(228 100% 90%);
--_track-size: min(10px, 1ex);
--_progress: hsl(228 100% 50%);
--_radius: 1e3px;
--_indeterminate-track: linear-gradient(to right,
var(--_track) 45%,
var(--_progress) 0%,
var(--_progress) 55%,
var(--_track) 0%
);
--_indeterminate-track-size: 225% 100%;
--_indeterminate-track-animation: progress-loading 2s infinite ease;
/* reset */
appearance: none;
border: none;
/* custom style */
position: relative;
height: var(--_track-size);
border-radius: var(--_radius);
overflow: hidden;
@media (prefers-color-scheme: dark) {
--_track: hsl(228 20% 30%);
--_progress: hsl(228 100% 75%);
}
&:focus-visible {
outline-color: var(--_progress);
}
/* Safari/Chromium */
&[value]::-webkit-progress-bar {
background-color: var(--_track);
}
&[value]::-webkit-progress-value {
background-color: var(--_progress);
transition: inline-size .25s ease-out;
}
/* Firefox */
&[value]::-moz-progress-bar {
background-color: var(--_progress);
}
/* indeterminate */
&:indeterminate::after {
content: "";
inset: 0;
position: absolute;
background: var(--_indeterminate-track);
background-size: var(--_indeterminate-track-size);
background-position: right;
animation: var(--_indeterminate-track-animation);
}
/* indeterminate Safari */
&:indeterminate::-webkit-progress-bar {
background: var(--_indeterminate-track);
background-size: var(--_indeterminate-track-size);
background-position: right;
animation: var(--_indeterminate-track-animation);
}
/* indeterminate Firefox */
&:indeterminate::-moz-progress-bar {
background: var(--_indeterminate-track);
background-size: var(--_indeterminate-track-size);
background-position: right;
animation: var(--_indeterminate-track-animation);
}
/* complete */
&:not([max])[value="1"]::before,
&[max="100"][value="100"]::before {
content: "✓";
position: absolute;
inset-block: 0;
inset-inline: auto 0;
display: flex;
align-items: center;
padding-inline-end: max(calc(var(--_track-size) / 4), 3px);
color: white;
font-size: calc(var(--_track-size) / 1.25);
}
}
@keyframes progress-loading {
50% {
background-position: left;
}
}
JS
const progress = document.querySelector('progress')
const zone = document.querySelector('#loading-zone')
const state = {
val: .1
}
const roundDecimals = (val, places) =>
+(Math.round(val + "e+" + places) + "e-" + places)
const setProgress = () => {
// set loading zone status
zone.setAttribute('aria-busy', state.val < 1)
// clear attributes if no value to show
//
if (state.val === null) {
progress.removeAttribute('aria-valuenow')
progress.removeAttribute('value')
progress.focus()
return
}
// round bad JS decimal math
const val = roundDecimals(state.val, 2)
const valPercent = val * 100 + "%"
// set value for screenreaders and element values
progress.value = val
progress.setAttribute('aria-valuenow', valPercent)
progress.innerText = valPercent
// focus so screenreaders hear the announced value update
progress.focus()
}
Except as otherwise noted, the content of this page is licensed under the Creative Commons Attribution 4.0 License, and code samples are licensed under the Apache 2.0 License. For details, see the Google Developers Site Policies. Java is a registered trademark of Oracle and/or its affiliates.
Last updated 2023-07-05 UTC.
[[["Easy to understand","easyToUnderstand","thumb-up"],["Solved my problem","solvedMyProblem","thumb-up"],["Other","otherUp","thumb-up"]],[["Missing the information I need","missingTheInformationINeed","thumb-down"],["Too complicated / too many steps","tooComplicatedTooManySteps","thumb-down"],["Out of date","outOfDate","thumb-down"],["Samples / code issue","samplesCodeIssue","thumb-down"],["Other","otherDown","thumb-down"]],["Last updated 2023-07-05 UTC."],[],[]]