javascript - About how to write promise

Question

I’m not very familiar with how to write Promise. I hope I can encapsulate some common states of reject and resolve. How can I write it better?
And the following writeFile Is it better to write it directly as a normal function? Sorry for posting the long code, please help. . . . Thanks

Answer 1

Asynchronous operations are best to require promise 或者 Generator 函数 或者是 asyncfunctions

var readFile = function (fileName) {
  return new Promise(function (resolve, reject) {
    fs.readFile(fileName, function(error, data) {
      if (error) reject(error);
      resolve(data);
    });
  });
};

Jiang Zi is simpler! Then put all the data processing logic inside the calling then 或者 catch