箭头函数与promise

 console.log("普通函数方式");
      var arr1 = [1, 2, 3, 4, 5];
      arr1.forEach(function(e) {
        console.log(e);
      });

      console.log("箭头函数方式");
      var arr2 = [1, 2, 3, 4, 5];
      arr2.forEach((e) => console.log(e));

 function taskA() {
        console.log("Task A");
        // throw new Error("taskA掉坑里了");
      }
      function taskB() {
        console.log("Task B");
        throw new Error("taskB掉坑里了");
      }
      function onRejected(error) {
        console.log("onRejected catch Error: A or B", error);
      }
      function finalTask() {
        console.log("Final Task");
      }

      var promise = Promise.resolve();
      promise
        .then(taskA)                // 和task A/B
        .then(taskB)
        .catch(onRejected)
        .then(finalTask);
     console.log('promise finish');   // promise finish 打印顺序