kopia lustrzana https://github.com/shoelace-style/shoelace
3.1 KiB
3.1 KiB
Mutation Observer
[component-header:sl-mutation-observer]
The Mutation Observer component offers a thin, declarative interface to the MutationObserver API
.
The mutation observer will report changes to the content it wraps through the sl-mutation
event. When emitted, a collection of MutationRecord objects will be attached to event.detail
that contains information about how it changed.
<div class="mutation-overview">
<sl-mutation-observer attr>
<sl-button type="primary">Click to mutate</sl-button>
</sl-mutation-observer>
<br>
👆 Click the button and watch the console
<script>
const container = document.querySelector('.mutation-overview');
const mutationObserver = container.querySelector('sl-mutation-observer');
const button = container.querySelector('sl-button');
const types = ['primary', 'success', 'neutral', 'warning', 'danger'];
let clicks = 0;
// Change the button's type attribute
button.addEventListener('click', () => {
clicks++;
button.setAttribute('type', types[clicks % types.length]);
});
// Log mutations
mutationObserver.addEventListener('sl-mutation', event => {
console.log(event.detail);
});
</script>
<style>
.mutation-overview sl-button {
margin-bottom: 1rem;
}
</style>
</div>
?> When you create a mutation observer, you must indicate what changes it should respond to by including at least one of attr
, child-list
, or char-data
. If you don't specify at least one of these attributes, no mutation events will be emitted.
Examples
Child List
Use the child-list
attribute to watch for new child elements that are added or removed.
<div class="mutation-child-list">
<sl-mutation-observer child-list>
<div class="buttons">
<sl-button type="primary">Add button</sl-button>
</div>
</sl-mutation-observer>
👆 Add and remove buttons and watch the console
<script>
const container = document.querySelector('.mutation-child-list');
const mutationObserver = container.querySelector('sl-mutation-observer');
const buttons = container.querySelector('.buttons');
const button = container.querySelector('sl-button[type="primary"]');
let i = 0;
// Add a button
button.addEventListener('click', () => {
const button = document.createElement('sl-button');
button.textContent = ++i;
buttons.append(button);
});
// Remove a button
buttons.addEventListener('click', event => {
const target = event.target.closest('sl-button:not([type="primary"])');
event.stopPropagation();
if (target) {
target.remove();
}
});
// Log mutations
mutationObserver.addEventListener('sl-mutation', event => {
console.log(event.detail);
});
</script>
<style>
.mutation-child-list .buttons {
display: flex;
gap: .25rem;
flex-wrap: wrap;
margin-bottom: 1rem;
}
</style>
</div>
[component-metadata:sl-mutation-observer]