跳到主要内容

1 篇博文 含有标签「async」

查看所有标签

· 阅读需 1 分钟

REF: https://www.youtube.com/watch?v=zoZiQJ38bXk

Normal Promise​

./hello.js
function sendRequest() {
  return new Promise(function(resolve, reject){
    setTimeout(function(){
      resolve("Lintao")
    }, 2000)
  });
}

let promise = sendRequest();
promise.then(function(username) {
  console.log(username)
})

Change to Await​

./hello-await.js
function sendRequest() {
    return new Promise(function(resolve, reject) {
        setTimeout(function() {
            resolve("Lintao");
        }, 2000);
    });
}


// must put await inside async function
async function getUsername() {
    // put await in front of a function which returns a Promise object
    console.log(await sendRequest());
}

getUsername()

Error handling​

./hello-await-error-handling.js
function sendRequest() {
    return new Promise(function(resolve, reject) {
        setTimeout(function() {
            reject("Lintao");
        }, 2000);
    });
}

async function getUsername() {
    // put inside try..catch block
    try {
        console.log(await sendRequest());
    } catch (error) {
        console.log(`error: ${error}`);
    }
}

getUsername();

With Fetch​

./hello-await-fetch.js
function sendRequest() {
    return new Promise(function(resolve, reject) {
        setTimeout(function() {
            reject("Lintao");
        }, 2000);
    });
}

async function getUsername() {
    // put inside try..catch block
    try {
        let username = await fetch('https://jsonplaceholder.typicode.com/users')
        username = await username.json()
        console.log(username);
    } catch (error) {
        console.log(`error: ${error}`);
    }
}

getUsername();

Promise.all and typescript​

REF: https://blog.logrocket.com/async-await-in-typescript/