Mike Schilling的错误处理解决方案，为错误事件处理程序提供了一个快捷方式。

function copyFile(source, target, cb) {
  var cbCalled = false;

  var rd = fs.createReadStream(source);
  rd.on("error", done);

  var wr = fs.createWriteStream(target);
  wr.on("error", done);
  wr.on("close", function(ex) {
    done();
  });
  rd.pipe(wr);

  function done(err) {
    if (!cbCalled) {
      cb(err);
      cbCalled = true;
    }
  }
}

Mike Schilling的错误处理解决方案，为错误事件处理程序提供了一个快捷方式。

function copyFile(source, target, cb) {
  var cbCalled = false;

  var rd = fs.createReadStream(source);
  rd.on("error", done);

  var wr = fs.createWriteStream(target);
  wr.on("error", done);
  wr.on("close", function(ex) {
    done();
  });
  rd.pipe(wr);

  function done(err) {
    if (!cbCalled) {
      cb(err);
      cbCalled = true;
    }
  }
}

相同的机制，但这增加了错误处理:

function copyFile(source, target, cb) {
  var cbCalled = false;

  var rd = fs.createReadStream(source);
  rd.on("error", function(err) {
    done(err);
  });
  var wr = fs.createWriteStream(target);
  wr.on("error", function(err) {
    done(err);
  });
  wr.on("close", function(ex) {
    done();
  });
  rd.pipe(wr);

  function done(err) {
    if (!cbCalled) {
      cb(err);
      cbCalled = true;
    }
  }
}

自Node.js 8.5.0以来，我们有了新的fs. js。copyFile和fs。copyFileSync方法。

使用的例子:

var fs = require('fs');

// File "destination.txt" will be created or overwritten by default.
fs.copyFile('source.txt', 'destination.txt', (err) => {
    if (err) 
        throw err;
    console.log('source.txt was copied to destination.txt');
});

如果你不关心它是否是异步的，并且不复制千兆字节大小的文件，并且宁愿不为单个函数添加另一个依赖项:

function copySync(src, dest) {
  var data = fs.readFileSync(src);
  fs.writeFileSync(dest, data);
}

编写速度快，使用方便，有承诺和错误管理:

function copyFile(source, target) {
  var rd = fs.createReadStream(source);
  var wr = fs.createWriteStream(target);
  return new Promise(function(resolve, reject) {
    rd.on('error', reject);
    wr.on('error', reject);
    wr.on('finish', resolve);
    rd.pipe(wr);
  }).catch(function(error) {
    rd.destroy();
    wr.end();
    throw error;
  });
}

async/await语法也是如此:

async function copyFile(source, target) {
  var rd = fs.createReadStream(source);
  var wr = fs.createWriteStream(target);
  try {
    return await new Promise(function(resolve, reject) {
      rd.on('error', reject);
      wr.on('error', reject);
      wr.on('finish', resolve);
      rd.pipe(wr);
    });
  } catch (error) {
    rd.destroy();
    wr.end();
    throw error;
  }
}