{"id":20563849,"url":"https://github.com/worker-tools/extendable-promise","last_synced_at":"2026-05-08T10:32:52.453Z","repository":{"id":57684658,"uuid":"476136743","full_name":"worker-tools/extendable-promise","owner":"worker-tools","description":"A promise that can be delayed (extended) via repeated calls to waitUntil.","archived":false,"fork":false,"pushed_at":"2022-05-27T11:21:52.000Z","size":33,"stargazers_count":1,"open_issues_count":0,"forks_count":1,"subscribers_count":1,"default_branch":"master","last_synced_at":"2025-06-21T10:42:27.982Z","etag":null,"topics":["javascript","promise"],"latest_commit_sha":null,"homepage":"https://workers.tools/extendable-promise","language":"TypeScript","has_issues":true,"has_wiki":null,"has_pages":null,"mirror_url":null,"source_name":null,"license":"mit","status":null,"scm":"git","pull_requests_enabled":true,"icon_url":"https://github.com/worker-tools.png","metadata":{"files":{"readme":"README.md","changelog":null,"contributing":null,"funding":null,"license":"LICENSE.md","code_of_conduct":null,"threat_model":null,"audit":null,"citation":null,"codeowners":null,"security":null,"support":null}},"created_at":"2022-03-31T03:28:38.000Z","updated_at":"2024-08-08T02:13:24.000Z","dependencies_parsed_at":"2022-09-17T00:20:54.774Z","dependency_job_id":null,"html_url":"https://github.com/worker-tools/extendable-promise","commit_stats":null,"previous_names":[],"tags_count":16,"template":false,"template_full_name":null,"purl":"pkg:github/worker-tools/extendable-promise","repository_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/worker-tools%2Fextendable-promise","tags_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/worker-tools%2Fextendable-promise/tags","releases_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/worker-tools%2Fextendable-promise/releases","manifests_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/worker-tools%2Fextendable-promise/manifests","owner_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners/worker-tools","download_url":"https://codeload.github.com/worker-tools/extendable-promise/tar.gz/refs/heads/master","sbom_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories/worker-tools%2Fextendable-promise/sbom","host":{"name":"GitHub","url":"https://github.com","kind":"github","repositories_count":264608135,"owners_count":23636684,"icon_url":"https://github.com/github.png","version":null,"created_at":"2022-05-30T11:31:42.601Z","updated_at":"2022-07-04T15:15:14.044Z","host_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub","repositories_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repositories","repository_names_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/repository_names","owners_url":"https://repos.ecosyste.ms/api/v1/hosts/GitHub/owners"}},"keywords":["javascript","promise"],"created_at":"2024-11-16T04:21:28.076Z","updated_at":"2026-05-08T10:32:47.425Z","avatar_url":"https://github.com/worker-tools.png","language":"TypeScript","funding_links":[],"categories":[],"sub_categories":[],"readme":"# Extendable Promise\n\nA promise that can be delayed (extended) via repeated calls to `waitUntil`.\n\n\"Extendable\" here refers to the ability to extend the duration of the promise, not inheritance/subtypes/etc. \nThe name and API are modelled after the\n[`ExtendableEvent`](https://developer.mozilla.org/en-US/docs/Web/API/ExtendableEvent)\ninterface that was introduced to the web part of the Service Worker API. As\nsuch, it provides a `waitUntil` method that takes a promise as argument that\nextends settlement of the parent promise until all promises that were\nadded in this way have settled. You can think about it like\n`Promise.allSettled`, except you can add promises to the list after the fact. Example:\n\n```js\nconst p = new ExtendablePromise(timeout(200).then(() =\u003e 1));\nawait timeout(100)\np.waitUntil(timeout(300).then(() =\u003e Promise.reject(Error('2'))));\n\nconst res = await p; // total duration ~400ms (100 + 300)\n\nassertEquals(res, [\n  { status: \"fulfilled\", value: 1 },\n  { status: \"rejected\", reason: Error('2') },\n]);\n```\n\nAfter all promises have settled, further calls to `waitUntil` become no-ops.\n\nThe constructor takes a promise as argument, which sets the minimum duration for the extendable promise. \n\nIf an extendable promise is created without supplying an initial promise, it is \"idle\" (`await`ing it pauses execution) until the first call to `waitUntil` \"primes\" it. \n\nInitializing it with a synchronous value or a settled promise immediately settles the extendable promise with that value and all calls to `waitUntil` are no-ops.\n\n--------\n\n\u003cp align=\"center\"\u003e\u003ca href=\"https://workers.tools\"\u003e\u003cimg src=\"https://workers.tools/assets/img/logo.svg\" width=\"100\" height=\"100\" /\u003e\u003c/a\u003e\n\u003cp align=\"center\"\u003eThis module is part of the Worker Tools collection\u003cbr/\u003e⁕\n\n[Worker Tools](https://workers.tools) are a collection of TypeScript libraries for writing web servers in [Worker Runtimes](https://workers.js.org) such as Cloudflare Workers, Deno Deploy and Service Workers in the browser. \n\nIf you liked this module, you might also like:\n\n- 🧭 [__Worker Router__][router] --- Complete routing solution that works across CF Workers, Deno and Service Workers\n- 🔋 [__Worker Middleware__][middleware] --- A suite of standalone HTTP server-side middleware with TypeScript support\n- 📄 [__Worker HTML__][html] --- HTML templating and streaming response library\n- 📦 [__Storage Area__][kv-storage] --- Key-value store abstraction across [Cloudflare KV][cloudflare-kv-storage], [Deno][deno-kv-storage] and browsers.\n- 🆗 [__Response Creators__][response-creators] --- Factory functions for responses with pre-filled status and status text\n- 🎏 [__Stream Response__][stream-response] --- Use async generators to build streaming responses for SSE, etc...\n- 🥏 [__JSON Fetch__][json-fetch] --- Drop-in replacements for Fetch API classes with first class support for JSON.\n- 🦑 [__JSON Stream__][json-stream] --- Streaming JSON parser/stingifier with first class support for web streams.\n\nWorker Tools also includes a number of polyfills that help bridge the gap between Worker Runtimes:\n- ✏️ [__HTML Rewriter__][html-rewriter] --- Cloudflare's HTML Rewriter for use in Deno, browsers, etc...\n- 📍 [__Location Polyfill__][location-polyfill] --- A `Location` polyfill for Cloudflare Workers.\n- 🦕 [__Deno Fetch Event Adapter__][deno-fetch-event-adapter] --- Dispatches global `fetch` events using Deno’s native HTTP server.\n\n[router]: https://workers.tools/router\n[middleware]: https://workers.tools/middleware\n[html]: https://workers.tools/html\n[kv-storage]: https://workers.tools/kv-storage\n[cloudflare-kv-storage]: https://workers.tools/cloudflare-kv-storage\n[deno-kv-storage]: https://workers.tools/deno-kv-storage\n[kv-storage-polyfill]: https://workers.tools/kv-storage-polyfill\n[response-creators]: https://workers.tools/response-creators\n[stream-response]: https://workers.tools/stream-response\n[json-fetch]: https://workers.tools/json-fetch\n[json-stream]: https://workers.tools/json-stream\n[request-cookie-store]: https://workers.tools/request-cookie-store\n[extendable-promise]: https://workers.tools/extendable-promise\n[html-rewriter]: https://workers.tools/html-rewriter\n[location-polyfill]: https://workers.tools/location-polyfill\n[deno-fetch-event-adapter]: https://workers.tools/deno-fetch-event-adapter\n\nFore more visit [workers.tools](https://workers.tools).\n","project_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fworker-tools%2Fextendable-promise","html_url":"https://awesome.ecosyste.ms/projects/github.com%2Fworker-tools%2Fextendable-promise","lists_url":"https://awesome.ecosyste.ms/api/v1/projects/github.com%2Fworker-tools%2Fextendable-promise/lists"}