Question

我做了一个简单的睡眠承诺功能：

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

然后在karma chai

中使用await / async

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()

代码可以在第二个等待中使用。

'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'}

抛出TypeError，但正如您所看到的，sleep函数从不拒绝Promise。另一点是，第一个等待不会抛出异常。任何人都可以帮助我吗？

Babel config：

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

Answer 1

我遇到了同样的问题。

为babel添加async await支持可以帮助我。

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

并将此预设添加到babel选项：

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

请试试。

js等待抛出TypeError

1 个答案: