fs.readFile(path[, options], callback)


    异步地读取文件的全部内容。

    Asynchronously reads the entire contents of a file.

    import { readFile } from 'node:fs';
    
    readFile('/etc/passwd', (err, data) => {
      if (err) throw err;
      console.log(data);
    });

    The callback is passed two arguments (err, data), where data is the contents of the file.

    If no encoding is specified, then the raw buffer is returned.

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

    import { readFile } from 'node:fs';
    
    readFile('/etc/passwd', 'utf8', callback);

    When the path is a directory, the behavior of fs.readFile() and fs.readFileSync() is platform-specific. On macOS, Linux, and Windows, an error will be returned. On FreeBSD, a representation of the directory's contents will be returned.

    import { readFile } from 'node:fs';
    
    // macOS, Linux, and Windows
    readFile('<directory>', (err, data) => {
      // => [Error: EISDIR: illegal operation on a directory, read <directory>]
    });
    
    //  FreeBSD
    readFile('<directory>', (err, data) => {
      // => null, <data>
    });

    It is possible to abort an ongoing request using an AbortSignal. If a request is aborted the callback is called with an AbortError:

    import { readFile } from 'node:fs';
    
    const controller = new AbortController();
    const signal = controller.signal;
    readFile(fileInfo[0].name, { signal }, (err, buf) => {
      // ...
    });
    // When you want to abort the request
    controller.abort();

    The fs.readFile() function buffers the entire file. To minimize memory costs, when possible prefer streaming via fs.createReadStream().

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