Merge pull request #19830 from overleaf/ae-iterator-polyfill

Always use ReadableStream asyncIterator polyfill

GitOrigin-RevId: 660a7316a549fe4ce4fc6bd1ef1a7d7e58759f14

services/web/frontend/js/features/pdf-preview/util/output-files.js

@@ -3,6 +3,7 @@ import BibLogParser from '../../../ide/log-parser/bib-log-parser'
 import { enablePdfCaching } from './pdf-caching-flags'
 import { debugConsole } from '@/utils/debugging'
 import { dirname, findEntityByPath } from '@/features/file-tree/util/path'
+import '@/utils/readable-stream-async-iterator-polyfill'
 
 // Warnings that may disappear after a second LaTeX pass
 const TRANSIENT_WARNING_REGEX = /^(Reference|Citation).+undefined on input line/

services/web/frontend/js/utils/readable-stream-async-iterator-polyfill.ts

@@ -0,0 +1,44 @@
+// @ts-nocheck
+/**
+ * A polyfill for `ReadableStream.protototype[Symbol.asyncIterator]`,
+ * aligning as closely as possible to the specification.
+ *
+ * from https://gist.github.com/MattiasBuelens/496fc1d37adb50a733edd43853f2f60e
+ *
+ * @see https://streams.spec.whatwg.org/#rs-asynciterator
+ * @see https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream#async_iteration
+ */
+
+ReadableStream.prototype.values ??= function ({ preventCancel = false } = {}) {
+  const reader = this.getReader()
+  return {
+    async next() {
+      try {
+        const result = await reader.read()
+        if (result.done) {
+          reader.releaseLock()
+        }
+        return result
+      } catch (e) {
+        reader.releaseLock()
+        throw e
+      }
+    },
+    async return(value) {
+      if (!preventCancel) {
+        const cancelPromise = reader.cancel(value)
+        reader.releaseLock()
+        await cancelPromise
+      } else {
+        reader.releaseLock()
+      }
+      return { done: true, value }
+    },
+    [Symbol.asyncIterator]() {
+      return this
+    },
+  }
+}
+
+ReadableStream.prototype[Symbol.asyncIterator] ??=
+  ReadableStream.prototype.values