fs.writeFile(file, data[, options], callback)

• file <string> | <Buffer> | <URL> | <integer> 文件名或文件描述符
• data <string> | <Buffer> | <TypedArray> | <DataView> | <Object>
• options <Object> | <string>
  • encoding <string> | <null> 默认值: 'utf8'
  • mode <integer> 默认值: 0o666
  • flag <string> 请参阅对文件系统 flags 的支持。 默认值: 'w'。
  • signal <AbortSignal> 允许中止正在进行的写入文件
• callback <Function>
  • err <Error>

当 file 是文件名时，将数据异步地写入文件，如果文件已存在则替换该文件。 data 可以是字符串或缓冲区。

当 file 是文件描述符时，其行为类似于直接调用 fs.write()（推荐）。 请参阅以下有关使用文件描述符的说明。

如果 data 是缓冲区，则忽略 encoding 选项。

mode 选项仅影响新创建的文件。 有关详细信息，请参阅 fs.open()。

如果 data 是普通的对象，则它必须具有自有的（不是继承的）toString 函数属性。

import { writeFile } from 'fs';

const data = new Uint8Array(Buffer.from('Hello Node.js'));
writeFile('message.txt', data, (err) => {
  if (err) throw err;
  console.log('The file has been saved!');
});

如果 options 是字符串，则它指定编码：

import { writeFile } from 'fs';

writeFile('message.txt', 'Hello Node.js', 'utf8', callback);

在同一个文件上多次使用 fs.writeFile() 而不等待回调是不安全的。 对于这种情况，建议使用 fs.createWriteStream()。

与 fs.readFile 类似，fs.writeFile 是一个便捷的方法，其在内部执行多次 write 调用以写入传给它的缓冲区。 对于性能敏感的代码，则考虑使用 fs.createWriteStream()。

可以使用 <AbortSignal> 取消 fs.writeFile()。 取消是"尽力而为"的，并且可能仍会写入一些数据。

import { writeFile } from 'fs';

const controller = new AbortController();
const { signal } = controller;
const data = new Uint8Array(Buffer.from('Hello Node.js'));
writeFile('message.txt', data, { signal }, (err) => {
  // 当请求中止时 - 使用 AbortError 调用回调
});
// 当应该中止请求时
controller.abort();

中止正在进行的请求不会中止单个操作系统请求，而是中止内部缓冲的 fs.writeFile 执行。

• file <string> | <Buffer> | <URL> | <integer> filename or file descriptor
• data <string> | <Buffer> | <TypedArray> | <DataView> | <Object>
• options <Object> | <string>
  • encoding <string> | <null> Default: 'utf8'
  • mode <integer> Default: 0o666
  • flag <string> See support of file system flags. Default: 'w'.
  • signal <AbortSignal> allows aborting an in-progress writeFile
• callback <Function>
  • err <Error>

When file is a filename, asynchronously writes data to the file, replacing the file if it already exists. data can be a string or a buffer.

When file is a file descriptor, the behavior is similar to calling fs.write() directly (which is recommended). See the notes below on using a file descriptor.

The encoding option is ignored if data is a buffer.

The mode option only affects the newly created file. See fs.open() for more details.

If data is a plain object, it must have an own (not inherited) toString function property.

import { writeFile } from 'fs';

const data = new Uint8Array(Buffer.from('Hello Node.js'));
writeFile('message.txt', data, (err) => {
  if (err) throw err;
  console.log('The file has been saved!');
});

If options is a string, then it specifies the encoding:

import { writeFile } from 'fs';

writeFile('message.txt', 'Hello Node.js', 'utf8', callback);

It is unsafe to use fs.writeFile() multiple times on the same file without waiting for the callback. For this scenario, fs.createWriteStream() is recommended.

Similarly to fs.readFile - fs.writeFile is a convenience method that performs multiple write calls internally to write the buffer passed to it. For performance sensitive code consider using fs.createWriteStream().

It is possible to use an <AbortSignal> to cancel an fs.writeFile(). Cancelation is "best effort", and some amount of data is likely still to be written.

import { writeFile } from 'fs';

const controller = new AbortController();
const { signal } = controller;
const data = new Uint8Array(Buffer.from('Hello Node.js'));
writeFile('message.txt', data, { signal }, (err) => {
  // When a request is aborted - the callback is called with an AbortError
});
// When the request should be aborted
controller.abort();

Aborting an ongoing request does not abort individual operating system requests but rather the internal buffering fs.writeFile performs.