ES6发生器 - 他们真的是异步/等待的替代品吗？ [英] ES6 generators- are they really an alternative to async/await?

问题描述

此 typescript博客文章说：

One of the posts in the comments section of this typescript blog post says:

如果我必须等到2.0为ES6发电机支持，我只需要
粘贴Traceur。发电机是一件很大的事情，他们使用诸如Koa，Co，Bluebird，
等的图书馆给你
async / await支持

Async / await关键字将允许应用程序保留类似于同步代码的逻辑结构。如何使用发电机来完成类似的事情？例如，如何将生成器与ajax调用结合使用以产生避免使用回调的同步样式代码？

Async/await keywords would allow applications to retain a logical structure that resembles synchronous code. How would one use a generator to accomplish something similar? For example, how would you use a generator in conjunction with an ajax call to produce synchronous style code that avoids using callbacks?

推荐答案

你只需要用一个帮助函数来抽象。

You just have to abstract that with an helper function.

假设jQuery：

function ajax(type, url, data){
  $.ajax({
    url: url,
    data: data,
    type: type
  })
  .done(function(data) {
    iterator.next(data);
  })
  .fail(function() {
    iterator.throw();
  });
}
var get = ajax.bind(null, 'GET');
var post = ajax.bind(null, 'POST');
var put = ajax.bind(null, 'PUT');
var patch = ajax.bind(null, 'PATCH');
var del = ajax.bind(null, 'DELETE');

function *asyncGet() {
  var URL = 'https://api.stackexchange.com/2.2/answers?order=desc&sort=activity&site=stackoverflow'
  var data = yield get(URL);
  console.log(data);
}

var iterator = asyncGet();
iterator.next();

另一个使用 setTimeout 的示例：

function delayReturn(time, val){
  setTimeout(function(){
    iterator.next(val);
  }, time);
}
var delayReturn1s = delayReturn.bind(null, 1000);

function *main() {
  console.log(yield delayReturn1s('Lolcat'));
}

var iterator = main();
iterator.next()

当然，您可以抽象出这样的迭代器传递：

Of course you can abstract the iterator passing with something like this:

var async = function(generator){
  var resume = function(err, data){
    if (err) iterator.throw();
    iterator.next(data);
  }
  var iterator = generator(resume);
  iterator.next();
}

然后你可以简单地：

function ajax(type, url, data, cb){
  $.ajax({
    url: url,
    data: data,
    type: type
  })
  .done(function(data) {
    cb(null, data)
  })
  .fail(function() {
    cb(arguments);
  });
}
var get = ajax.bind(null, 'GET');
var post = ajax.bind(null, 'POST');
var put = ajax.bind(null, 'PUT');
var patch = ajax.bind(null, 'PATCH');
var del = ajax.bind(null, 'DELETE');

async(function *(resume) {
  var URL = 'https://api.stackexchange.com/2.2/answers?order=desc&sort=activity&site=stackoverflow'
  var data = yield get(URL, null, resume);
  console.log(data);
});

这篇关于ES6发生器 - 他们真的是异步/等待的替代品吗？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！