js等待抛出TypeError

Question

I make a simple sleep promise function:

let sleep = function(time) {
  return new Promise(function (resolve) {
    setTimeout(function () {
        resolve();
    }, time);
  })
}

then use await/async in karma with chai

var test = async function() {

  // works  
  await sleep(DELAY)

  let secondItem = vm.$el.querySelectorAll('.el-table__row')[1]
  let secondItemTds = secondItem.querySelectorAll('td')

  // throw exception
  await sleep(DELAY)
  secondItemTds[0].click()
  expect(rowClickCnt).equal(0)

  // if I CATCH the above exception, here throw exception again
  await sleep(DELAY)
  secondItem[5].click()
  expect(rowClickCnt).equal(1)
}

test()

The code can work util the second await.

'Unhandled promise rejection', TypeError{stack: '_callee$@http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59:53913:30
tryCatch@http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59:14058:44
invoke@http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59:14296:30
http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59:14110:28
step@http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59:51395:30
http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59:51406:17
run@http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59:50996:29
http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59:51009:31
flush@http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59:50498:11', line: 53913, sourceURL: 'http://localhost:9876/base/index.js?312a09ec6fd4038632c2250d472217bc6ee69c59'}

A TypeError is thrown, but as you can see, the sleep function never reject the Promise . Another point is that the first await doesn't throw Exception. Anyone can help me out?

Babel config:

{
  "presets": [
    ["env", { "modules": false }],
    "stage-2"
  ],
  "plugins": ["transform-runtime"],
  "comments": false,
  "env": {
    "test": {
      "presets": ["env", "stage-2"],
      "plugins": [ "istanbul" ]
    }
  }
}

Answer 1

I have had the same problem.

Adding support of async await to babel helps me.

npm install --save-dev babel-preset-es2017

And add this preset to babel options:

"presets": [ <your presets> , "es2017"]

Try it please.