@cran/lib.vue.ref/src/watch/watchFilter.ts

Vue Reactivity Extensions

import { type WatchCallback, type WatchOptions, type WatchSource, watch } from "vue";

/**
 * @since 0.0.1
 * @category Watch
 */
export function watchFilter<T, Immediate extends Readonly<boolean> = false> (
  source: WatchSource<T>,
  filter: T | ((
    ...args: Parameters<WatchCallback<
    T, Immediate extends true ? T | undefined : T
    >>
  ) => boolean),
  cb: WatchCallback<T, Immediate extends true ? T | undefined : T>,
  options?: WatchOptions<Immediate>
) {
  const filterFn = filter instanceof Function
    ? filter : function filterFn ( next: T ) { return next === filter; };

  return watch(source, function onSourceChange ( ...args ) {
    if (filterFn(...args)) { cb(...args); }
  }, options);
}