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guard against NPEs for IntersectionObserver

This commit is contained in:
Nolan Lawson 2018-01-23 21:02:51 -08:00
parent 2a215480e2
commit 0a7f56004f
1 changed files with 13 additions and 7 deletions
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20
routes/_utils/AsyncLayout.js
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@ -14,24 +14,30 @@ class AsyncLayout {
}
observe(key, node, callback) {
this._onIntersectionCallbacks[key] = (entry) => {
callback(getRectFromEntry(entry))
this.unobserve(key, node)
if (this._intersectionObserver) {
this._onIntersectionCallbacks[key] = (entry) => {
callback(getRectFromEntry(entry))
this.unobserve(key, node)
}
this._intersectionObserver.observe(node)
}
this._intersectionObserver.observe(node)
}
unobserve(key, node) {
if (key in this._onIntersectionCallbacks) {
return
}
this._intersectionObserver.unobserve(node)
if (this._intersectionObserver) {
this._intersectionObserver.unobserve(node)
}
delete this._onIntersectionCallbacks[key]
}
disconnect() {
this._intersectionObserver.disconnect()
this._intersectionObserver = null
if (this._intersectionObserver) {
this._intersectionObserver.disconnect()
this._intersectionObserver = null
}
}
}