36 lines
921 B
JavaScript
36 lines
921 B
JavaScript
// Use intersection observer to calculate rects asynchronously
|
|
class AsyncLayout {
|
|
constructor(generateKeyFromNode) {
|
|
this._onIntersectionCallbacks = {}
|
|
|
|
this._intersectionObserver = new IntersectionObserver(entries => {
|
|
entries.forEach(entry => {
|
|
let key = generateKeyFromNode(entry.target)
|
|
this._onIntersectionCallbacks[key](entry)
|
|
})
|
|
})
|
|
}
|
|
|
|
observe(key, node, callback) {
|
|
this._onIntersectionCallbacks[key] = (entry) => {
|
|
callback(entry.boundingClientRect)
|
|
this.unobserve(key, node)
|
|
}
|
|
this._intersectionObserver.observe(node)
|
|
}
|
|
|
|
unobserve(key, node) {
|
|
if (key in this._onIntersectionCallbacks) {
|
|
return
|
|
}
|
|
this._intersectionObserver.unobserve(node)
|
|
delete this._onIntersectionCallbacks[key]
|
|
}
|
|
|
|
disconnect() {
|
|
this._intersectionObserver.disconnect()
|
|
this._intersectionObserver = null
|
|
}
|
|
}
|
|
|
|
export { AsyncLayout } |