filehandle.truncate(len)

• len <integer> 默认值：0

  ¥len <integer> Default: 0

• 返回：<Promise> 成功时将使用 undefined 履行。

  ¥Returns: <Promise> Fulfills with undefined upon success.

截断文件。

¥Truncates the file.

如果文件大于 len 个字节，则仅前 len 个字节将保留在文件中。

¥If the file was larger than len bytes, only the first len bytes will be retained in the file.

下面的示例仅保留文件的前四个字节：

¥The following example retains only the first four bytes of the file:

import { open } from 'node:fs/promises';

let filehandle = null;
try {
  filehandle = await open('temp.txt', 'r+');
  await filehandle.truncate(4);
} finally {
  await filehandle?.close();
} 拷贝

如果文件先前小于 len 个字节，则将其扩展，并且扩展部分将使用空字节（'\0'）填充：

¥If the file previously was shorter than len bytes, it is extended, and the extended part is filled with null bytes ('\0'):

如果 len 为负数，则将使用 0。

¥If len is negative then 0 will be used.