Created: Design Cancellable Function - Solution

Author: arindal1

L-A/0010 Design Cancellable Function (L-A)/Design Cancellable Function.js

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+const cancellable = (generator) => {
+  let cancel;
+  const cancelPromise = new Promise((_, reject) => {
+    cancel = () => reject("Cancelled");
+  });
+  // Every Promise rejection has to be caught.
+  cancelPromise.catch(() => {});
+
+  const promise = (async () => {
+    let next = generator.next();
+    while (!next.done) {
+      try {
+        next = generator.next(await Promise.race([next.value, cancelPromise]));
+      } catch (e) {
+        next = generator.throw(e);
+      }
+    }
+    return next.value;
+  })();
+
+  return [cancel, promise];
+};