一种通过async/await实现函数同步执行的方式

const testArr = [
  () => {
    return new Promise((resolve, reject) => {
      setTimeout(()=> {
        alert(1);
        resolve();
      }, 300);
    });
  },
  () => {
    return new Promise((resolve, reject) => {
      setTimeout(()=> {
        alert(2);
        resolve();
      }, 500);
    });
  },
  () => {
    return new Promise((resolve, reject) => {
      setTimeout(()=> {
        alert(3);
        resolve();
      }, 100);
    });
  }
];

async function iterate(arr) {
  let index = 0;
  while (index < arr.length - 1) {
    await arr[index]();
    index += 1;
  }
  return arr[index]();
}

iterate(testArr);

建议在https://codepen.io/pen上执行查看，挂载https://cdn.bootcss.com/babel-polyfill/7.0.0-alpha.12/polyfill.js

若您嫌麻烦，直接点这里: https://codepen.io/timrchen/pen/NggaEj