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