将嵌套的 promise 转换为 async/await 语法

Question

I have a nested promise that fetches data and then presents it to the DOM.

I am trying to convert it into an async/await syntax, but because it is nested with a Promise.All I am having trouble converting it.

    fetch(searchUrl)
        .then(function (response) {
          return response.json()
        })
        .then(function (data) {
          searchLoader.style.display = "none";
          for (let i = 0; i < 10; i++) {
            let stock = `${data[i].name}, (${data[i].symbol})`;
            listOfStocks.innerHTML += `<li class="list-group-item"><a href="./company.html?symbol=${data[i].symbol}">${stock}<a/></li>`;
            // console.log(data[i].symbol)
          }
          return Promise.all(data.map(item => fetch(`${BaseUrl}company/profile/${item.symbol}`)));
        })
        .then(function (response) {
          return Promise.all(response.map(x => x.json()));
        })
        .then(function (data1) {
          console.log(data1);
          for (let i = 0; i < listOfStocks.children.length; i++) {
            if (data1[i].profile.changes >= 0) {
              listOfStocks.children[i].innerHTML = `<img class="logo-for-list" src="${data1[i].profile.image}" /> ${listOfStocks.children[i].innerHTML} <span class="color-prc" style="color:green;"> ${data1[i].profile.changesPercentage}</span>`;
            } else {
              listOfStocks.children[i].innerHTML = `<img class="logo-for-list" src="${data1[i].profile.image}" /> ${listOfStocks.children[i].innerHTML} <span class="color-prc"> ${data1[i].profile.changesPercentage}</span>`;
            }
          }

Thanks

Answer 1

it seems to be working @bergi - thanks for the pointer

  const response = await fetch(searchUrl);
      const data = await response.json();

      searchLoader.style.display = "none";
      for (let i = 0; i < 10; i++) {
        let stock = `${data[i].name}, (${data[i].symbol})`;
        listOfStocks.innerHTML += `<li class="list-group-item"><a href="./company.html?symbol=${data[i].symbol}">${stock}<a/></li>`;
        // console.log(data[i].symbol)
      }
      const response1 = await Promise.all(data.map(item => fetch(`${BaseUrl}company/profile/${item.symbol}`)));

      const data1 = await Promise.all(response1.map(x => x.json()));

      for (let i = 0; i < listOfStocks.children.length; i++) {
        if (data1[i].profile.changes >= 0) {
          listOfStocks.children[i].innerHTML = `<img class="logo-for-list" src="${data1[i].profile.image}" /> ${listOfStocks.children[i].innerHTML} <span class="color-prc" style="color:green;"> ${data1[i].profile.changesPercentage}</span>`;
        } else {
          listOfStocks.children[i].innerHTML = `<img class="logo-for-list" src="${data1[i].profile.image}" /> ${listOfStocks.children[i].innerHTML} <span class="color-prc"> ${data1[i].profile.changesPercentage}</span>`;
        }
      }
    ```

Answer 2

This is how you would convert a Promise.then(...).then(...).then(....) chain to an async/await code:-

async function processStuff(){
  const data = await fetch(searchUrl).then((response)=>response.json());

  searchLoader.style.display = "none";

       for (let i = 0; i < 10; i++) {
            let stock = `${data[i].name}, (${data[i].symbol})`;
            listOfStocks.innerHTML += `<li class="list-group-item"><a href="./company.html?symbol=${data[i].symbol}">${stock}<a/></li>`;
            // console.log(data[i].symbol)
          }
          const response = await Promise.all(data.map(item => fetch(`${BaseUrl}company/profile/${item.symbol}`)));

          const data1 = await Promise.all(response.map(x => x.json()));

               for (let i = 0; i < listOfStocks.children.length; i++)             {
            if (data1[i].profile.changes >= 0) {
              listOfStocks.children[i].innerHTML = `<img class="logo-for-list" src="${data1[i].profile.image}" /> ${listOfStocks.children[i].innerHTML} <span class="color-prc" style="color:green;"> ${data1[i].profile.changesPercentage}</span>`;
            } else {
              listOfStocks.children[i].innerHTML = `<img class="logo-for-list" src="${data1[i].profile.image}" /> ${listOfStocks.children[i].innerHTML} <span class="color-prc"> ${data1[i].profile.changesPercentage}</span>`;
            }  
          
            }

}
processStuff();

Note - There is nothing special I did here for Promise.all() since it simply returns a Promise . Had it been just Promise.resolve(2) , the approach would be the same.

Answer 3

Should be something like this:

 try { const response = await fetch(searchURL) const data = await response.json() searchLoader.style.display = "none"; for (let i = 0; i < 10; i++) { let stock = `${data[i].name}, (${data[i].symbol})`; listOfStocks.innerHTML += `<li class="list-group-item"><a href="./company.html?symbol=${data[i].symbol}">${stock}<a/></li>`; // console.log(data[i].symbol) } const data1 = await Promise.all(data.map(async (item) => { const response = await fetch(`${BaseUrl}company/profile/${item.symbol}`) return response.json() })); for (let i = 0; i < listOfStocks.children.length; i++) { if (data1[i].profile.changes >= 0) { listOfStocks.children[i].innerHTML = `<img class="logo-for-list" src="${data1[i].profile.image}" /> ${listOfStocks.children[i].innerHTML} <span class="color-prc" style="color:green;"> ${data1[i].profile.changesPercentage}</span>`; } else { listOfStocks.children[i].innerHTML = `<img class="logo-for-list" src="${data1[i].profile.image}" /> ${listOfStocks.children[i].innerHTML} <span class="color-prc"> ${data1[i].profile.changesPercentage}</span>`; } } } catch (e) { console.log(e) }