chore: consolidate new foundation and archive v1 (#1495)

v1/packages/mosaic/framework/skills/vueuse-functions/references/useObservable.md

@@ -0,0 +1,66 @@
+---
+category: '@RxJS'
+---
+
+# useObservable
+
+Use an RxJS [`Observable`](https://rxjs.dev/guide/observable), return a `ref`, and automatically unsubscribe from it when the component is unmounted.
+
+## Usage
+
+<!-- TODO: import rxjs error if enable twoslash -->
+
+```ts no-twoslash
+import { useObservable } from '@vueuse/rxjs';
+import { interval } from 'rxjs';
+import { mapTo, scan, startWith } from 'rxjs/operators';
+
+// setup()
+const count = useObservable(
+  interval(1000).pipe(
+    mapTo(1),
+    startWith(0),
+    scan((total, next) => next + total),
+  ),
+);
+```
+
+If you want to add custom error handling to an `Observable` that might error, you can supply an optional `onError` configuration. Without this, RxJS will treat any error in the supplied `Observable` as an "unhandled error" and it will be thrown in a new call stack and reported to `window.onerror` (or `process.on('error')` if you happen to be in Node).
+
+```ts no-twoslash
+import { useObservable } from '@vueuse/rxjs';
+import { interval } from 'rxjs';
+import { map } from 'rxjs/operators';
+
+// setup()
+const count = useObservable(
+  interval(1000).pipe(
+    map((n) => {
+      if (n === 10) throw new Error('oops');
+
+      return n + n;
+    }),
+  ),
+  {
+    onError: (err) => {
+      console.log(err.message); // "oops"
+    },
+  },
+);
+```
+
+## Type Declarations
+
+```ts
+export interface UseObservableOptions<I> {
+  onError?: (err: any) => void;
+  /**
+   * The value that should be set if the observable has not emitted.
+   */
+  initialValue?: I | undefined;
+}
+export declare function useObservable<H, I = undefined>(
+  observable: Observable<H>,
+  options?: UseObservableOptions<I | undefined>,
+): Readonly<Ref<H | I>>;
+```