---
hide_title: false
hide_table_of_contents: false
pagination_next: null
pagination_prev: null
---
# FetchEvent.waitUntil()


The **`waitUntil()`** method tells the host environment that work is ongoing until the promise settles, and it shouldn't terminate
the application if it wants that work to complete.

The `waitUntil()` method must be initially called synchronously within the event callback,
but after that it can be called multiple times, and will hold the process open until all the promises passed to it
settle.

## Syntax

```js
waitUntil(promise)
```

### Parameters

A [`Promise`](../../Promise/Promise.mdx).

### Return value

None `undefined`.
