---
title: then
framework: CKTool JS
role: symbol
role_heading: Instance Method
platforms: [cktool js 1.2.15+]
path: cktooljs/cancellablepromise/then
---

# then

Tells CancellablePromise what callbacks to call on success or failure of the inner promise.

## Declaration

```data
CancellablePromise then(
	Function? onrejected,
	Function? onfullfilled
);
```

## Parameters

- `onrejected`: An optional function CancellablePromise calls when the inner promise rejects.
- `onfullfilled`: An optional function CancellablePromise calls when the inner promise resolves successfully.

## Discussion

Discussion If you provide a function for the onrejected parameter, CancellablePromise will call that function if the promise fails. If you provide a function for the onfulfilled parameter, CancellablePromise will call that function if the promise succeeds.