Function truncate

truncate(filePath: string, len: number): AsyncVoidIOResult
Truncates (resizes) a file to the specified size.

If len is smaller than the current file size, the file is shortened and the trailing data is discarded. If len is larger, the file is extended with zero bytes (\x00).

The file must already exist; this operation never creates a new file. Truncating a directory path returns a TypeMismatchError.
Parameters
- filePath: string
  The absolute path of the file to truncate.
- len: number
  The target size in bytes. Must be a non-negative integer.
Returns AsyncVoidIOResult
A promise that resolves to an AsyncVoidIOResult indicating success or failure.
Since
2.2.0

See
truncateSync for synchronous version
Example
```
await writeFile('/log.txt', 'Hello, World!');
await truncate('/log.txt', 5);   // file now contains "Hello"
await truncate('/log.txt', 8);   // file now contains "Hello\x00\x00\x00"
```
- Defined in async/core/truncate.ts:27