我正在尝试使用异步等待。
我的应用程序是这样启动的
axios.get(`${ROOT_URL}/ccidxann.php`)
.catch(err => console.error('axios error get', err))
.then(async res => {
const html = res.data
const jobList = await getJobList(html)
console.log(' after each jobList', jobList)
// jsonfile.writeFileSync('jobs.json', jobList, { flag: 'a' })
})
.catch(err => console.error(err))
问题是 jobList
始终作为空数组返回。
这是getJobList
功能
async function getJobList (html) {
const jobList = []
const dom = new JSDOM(html)
const { window } = dom
const $ = require('jquery')(window)
const jobsInDom = $('table').first().find('td > a')
// AWAIT HERE
await jobsInDom.each(async function (index, jobElem) {
const name = $(jobElem).text()
const url = $(jobElem).attr('href')
// Another AWAIT HERE
const jobDetailsHTML = await getJobDetailsHTML(`${ROOT_URL}/${url}`)
.catch(err => console.error('getJobDetailsHTML err', err))
const domDetails = new JSDOM(jobDetailsHTML)
const { window: windowDetails } = domDetails
const $details = require('jquery')(windowDetails)
const jobDetailsHTMLBody = $details('body').prop('outerHTML')
jobList.push({
_id: url,
name,
detailsHTML: jobDetailsHTMLBody
})
console.log('in each jobList', jobList)
}) //each
return jobList
}
正如你所看到的,我输入了 async
前面的关键字,
我已经输入了 async
each
回调中的关键字
并输入await
在所有异步操作之前。
console.log
在each
的回调中打印填充有值的数组
但似乎return
在 each
之前工作
即使有await
前面有关键字。
这里还有getJobDetailsHTML
万一。这是一个简单的功能,而且似乎工作得很好
async function getJobDetailsHTML (url) {
// ANOTHER AWAIT HERE
return await axios.get(url).data
}
最佳答案
我认为jobsInDom.each
是同步函数,因此在前面放置await不会给您带来预期的效果。因此,您需要以某种方式获得在所有作业处理完成后解决的 promise ,如下所示:
// handles one element and returns promise
const jobHandler = async jobElem => {
const name = $(jobElem).text()
const url = $(jobElem).attr('href')
const jobDetailsHTML = await getJobDetailsHTML(`${ROOT_URL}/${url}`)
.catch(err => console.error('getJobDetailsHTML err', err))
const domDetails = new JSDOM(jobDetailsHTML)
const { window: windowDetails } = domDetails
const $details = require('jquery')(windowDetails)
const jobDetailsHTMLBody = $details('body').prop('outerHTML')
jobList.push({
_id: url,
name,
detailsHTML: jobDetailsHTMLBody
})
console.log('in each jobList', jobList)
}
const promises = [];
// start processing of each element
jobsInDom.each((index, jobElem) => promises.push(jobHandler(jobElem));
// wait for processing of all job elements
await Promise.all(promises);
关于javascript - JS返回不等待await,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/50985577/