[js] Reduce GC pressure in TypeScript getAttribute and isDisplayed atoms#17582
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getAttribute: convert BOOLEAN_PROPERTIES from Array to Set for O(1) .has()
lookup instead of O(n) .indexOf(), and call element.getAttribute(name)
directly at the three call sites that already hold the lowercased name,
avoiding a redundant .toLowerCase() in the wrapper.
isDisplayed: replace findImageUsingMap's full-DOM getElementsByTagName('*')
scan with a single querySelector('[usemap="#..."]') call, using the same
CSS attribute-value escaping pattern applied to nameMany in find-elements.
…d atom Add three per-call Maps inside isShownElement, scoped to the single synchronous invocation so there is no stale-data risk and no GC pressure between calls: - computedStyleCache: getEffectiveStyle now fetches getComputedStyle once per element and reuses the CSSStyleDeclaration for subsequent property reads. A typical isShown call queries 5-8 properties on the same element. - clientRectCache: getClientRect caches the Rect after the first getBoundingClientRect (or imageMap rect) computation. Overflow checking and positiveSize both query ancestor rects, so shared containers are only laid out once. - displayedCache: displayed() walks the full ancestor chain on every call. positiveSize iterates all children calling displayedFn on each, so shared ancestors were re-walked N times for N siblings. The cache makes each ancestor node free after the first traversal.
document.createElement('script').async returns true by default (browser
sets the 'force async' flag on script elements created via JS), so the
test expecting null was never correct. The absent-boolean-returns-null
behaviour is already covered by the existing disabled and readonly tests.
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getAttribute: convert BOOLEAN_PROPERTIES from Array to Set for O(1) .has() lookup instead of O(n) .indexOf(), and call element.getAttribute(name) directly at the three call sites that already hold the lowercased name, avoiding a redundant .toLowerCase() in the wrapper.
isDisplayed: replace findImageUsingMap's full-DOM getElementsByTagName('*') scan with a single querySelector('[usemap="#..."]') call, using the same CSS attribute-value escaping pattern applied to nameMany in find-elements.
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