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avoid creating a div on every render in portal #4037

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Merged
merged 1 commit into from
Dec 8, 2023
Merged

avoid creating a div on every render in portal #4037

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5 changes: 5 additions & 0 deletions .changeset/weak-balloons-search.md
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Original file line number Diff line number Diff line change
@@ -0,0 +1,5 @@
---
'@primer/react': patch
---

Portal avoids useless createElement
23 changes: 13 additions & 10 deletions src/Portal/Portal.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -65,14 +65,18 @@ export const Portal: React.FC<React.PropsWithChildren<PortalProps>> = ({
onMount,
containerName: _containerName,
}) => {
const hostElement = document.createElement('div')
const elementRef = React.useRef<HTMLDivElement | null>(null)
if (!elementRef.current) {
const div = document.createElement('div')
// Portaled content should get their own stacking context so they don't interfere
// with each other in unexpected ways. One should never find themselves tempted
// to change the zIndex to a value other than "1".
div.style.position = 'relative'
div.style.zIndex = '1'
elementRef.current = div
}

// Portaled content should get their own stacking context so they don't interfere
// with each other in unexpected ways. One should never find themselves tempted
// to change the zIndex to a value other than "1".
hostElement.style.position = 'relative'
hostElement.style.zIndex = '1'
const elementRef = React.useRef(hostElement)
const element = elementRef.current
Comment on lines +68 to +79
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since we only used the ref, which is created on the first render, we can just create it on the first render.

this is still not SSR safe, however, and we should probably change this to account for that, but at least we're not wasting memory for no reason?


useLayoutEffect(() => {
let containerName = _containerName
Expand All @@ -87,15 +91,14 @@ export const Portal: React.FC<React.PropsWithChildren<PortalProps>> = ({
`Portal container '${_containerName}' is not yet registered. Container must be registered with registerPortal before use.`,
)
}
const element = elementRef.current
parentElement.appendChild(element)
onMount?.()

return () => {
parentElement.removeChild(element)
}
// eslint-disable-next-line react-hooks/exhaustive-deps
}, [elementRef])
}, [element])
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element is stable, so this is the same. I kind of wonder if the lack of exhaustive deps here indicates other issues, but ignoring that for now since this pr is keeping identical behavior characteristics, with just a bit less waste


return createPortal(children, elementRef.current)
return createPortal(children, element)
}