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45 lines
1.4 KiB
TypeScript
45 lines
1.4 KiB
TypeScript
/**
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* The `SubtreeRetainer` class keeps track of a number of pieces of data,
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* comparing the values of these pieces at every iteration.
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*
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* This is useful for preventing redraws to relatively static (or huge)
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* components whose VDOM only depends on very few values, when none of them
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* have changed.
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*
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* @example
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* // Check two callbacks for changes on each update
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* this.subtree = new SubtreeRetainer(
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* () => this.attrs.post.freshness,
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* () => this.showing
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* );
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*
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* // Add more callbacks to be checked for updates
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* this.subtree.check(() => this.attrs.user.freshness);
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*
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* // In a component's onbeforeupdate() method:
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* return this.subtree.needsRebuild()
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*
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* @see https://mithril.js.org/lifecycle-methods.html#onbeforeupdate
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*/
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export default class SubtreeRetainer {
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protected callbacks: (() => any)[];
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protected data: Record<string, any>;
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/**
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* @param callbacks Functions returning data to keep track of.
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*/
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constructor(...callbacks: (() => any)[]);
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/**
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* Return whether any data has changed since the last check.
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* If so, Mithril needs to re-diff the vnode and its children.
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*/
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needsRebuild(): boolean;
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/**
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* Add another callback to be checked.
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*/
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check(...callbacks: (() => any)[]): void;
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/**
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* Invalidate the subtree, forcing it to be redrawn.
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*/
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invalidate(): void;
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}
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