promise串行写法

[arcsin1]

• 实现的关键点就在于，在执行 executePromise 之前不会创建 promise

 function createPromise(fn) {
  return new Promise((resolve)=>{
      fn;
      resolve()
  });
}

function executePromises(createPromises) {
  var result = Promise.resolve();
  createPromises.forEach(function (createPromise) {
    result = result.then(createPromise);
  });
  return result;
}


executePromises([
createPromise(console.info('3')),
createPromise(console.info('2')),
createPromise(console.info('1')),
])