# Timer.cancel

## Function

Cancels the `Timer` object returned by `set_timeout()` or `set_interval()`. Returns `true` if the cancellation is successful, and `false` if it has been canceled or completed.

## Syntax

```bt
ok = timer.cancel()
```

## Parameters

| Parameters | Type | Required | Default value | Description |
| ------ | ------ | ------ | ------ | ------ |
| None | - | - | - | `cancel()` Does not accept parameters. |

## Return value

| Type | Description |
| ------ | ------ |
| Bool | The timer returns `true` if the event is successfully canceled, otherwise it returns `false`. |

## Example

```bt
timer = set_timeout(fn() {
    println(' will not execute ')
}, 1000)

ok = timer.cancel()

// Output: true
print ok
```

## Notes

- `cancel()` will not interrupt the callback in progress, it will only prevent subsequent triggering.
- After the timeout callback has started or completed, call `cancel()` to return `false`.
- When `self.cancel()` is called internally in the interval callback, the current callback will continue to execute and will not be scheduled in the future.