@tldraw/utils
Version:
tldraw infinite canvas SDK (private utilities).
44 lines (43 loc) • 1.44 kB
JavaScript
class WeakCache {
/**
* The internal WeakMap storage for cached key-value pairs.
*
* @public
*/
items = /* @__PURE__ */ new WeakMap();
/**
* Get the cached value for a given key, computing it if not already cached.
*
* Retrieves the cached value associated with the given key. If no cached
* value exists, calls the provided callback function to compute the value, stores it
* in the cache, and returns it. Subsequent calls with the same key will return the
* cached value without recomputation.
*
* @param item - The object key to retrieve the cached value for
* @param cb - Callback function that computes the value when not already cached
* @returns The cached value if it exists, otherwise the newly computed value from the callback
*
* @example
* ```ts
* const cache = new WeakCache<HTMLElement, DOMRect>()
* const element = document.getElementById('my-element')!
*
* // First call computes and caches the bounding rect
* const rect1 = cache.get(element, (el) => el.getBoundingClientRect())
*
* // Second call returns cached value
* const rect2 = cache.get(element, (el) => el.getBoundingClientRect())
* // rect1 and rect2 are the same object
* ```
*/
get(item, cb) {
if (!this.items.has(item)) {
this.items.set(item, cb(item));
}
return this.items.get(item);
}
}
export {
WeakCache
};
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