domain.intercept(callback)

• callback <Function> 回调函数

  ¥callback <Function> The callback function

• 返回：<Function> 截获的函数

  ¥Returns: <Function> The intercepted function

此方法和 domain.bind(callback) 差不多。但是，除了捕获抛出的错误外，它还会拦截作为第一个参数发送给函数的 Error 对象。

¥This method is almost identical to domain.bind(callback). However, in addition to catching thrown errors, it will also intercept Error objects sent as the first argument to the function.

这样，常见的 if (err) return callback(err); 模式可以在一个地方用单个错误句柄替换。

¥In this way, the common if (err) return callback(err); pattern can be replaced with a single error handler in a single place.

const d = domain.create();

function readSomeFile(filename, cb) {
  fs.readFile(filename, 'utf8', d.intercept((data) => {
    // Note, the first argument is never passed to the
    // callback since it is assumed to be the 'Error' argument
    // and thus intercepted by the domain.

    // If this throws, it will also be passed to the domain
    // so the error-handling logic can be moved to the 'error'
    // event on the domain instead of being repeated throughout
    // the program.
    return cb(null, JSON.parse(data));
  }));
}

d.on('error', (er) => {
  // An error occurred somewhere. If we throw it now, it will crash the program
  // with the normal line number and stack message.
}); 拷贝