如何触发 rejectionhandled 事件

Question

if(!window.onrejectionhandled) window.onrejectionhandled = function (){
    console.log('window.onrejectionhandled', '被捕获', arguments)
}

window.addEventListener('rejectionhandled', window.onrejectionhandled, true)


window.addEventListener("rejectionhandled", event => {
  console.log("Promise rejected; reason: " + event.reason);
}, false);

写了好几个都没触发。网上这个垃圾文章也看不明白。

chrome: 版本 96.0.4664.110（正式版本） (x86_64)

---

贴一堆测试代码

let promise1 = new Promise(function (reslove) {
    console.log(Date.now())
    setTimeout(() => {
        console.log(Date.now())
        reslove(Date.now())
    }, 500)
})
let promise2 = new Promise(function (reslove) {
    console.log(Date.now())
    setTimeout(() => {
        console.log(Date.now())
        reslove(Date.now())
    }, 800)
})
promise1.then(console.log)
Promise.resolve(promise1).then(console.log)
Promise.all([promise1, promise2]).then(console.log)


Promise.reject(1).then(console.log);
Promise.reject(2).then(console.log).catch(v => Promise.reject(3));
Promise.reject(2).then(console.log).catch(v => Promise.reject(3)).then(console.log);
Promise.reject(2).then(console.log).catch(v => v).then(console.log);
Promise.reject(4).then(console.log).catch(v => 5).then(console.log);

Promise.resolve(1).then(v => { const a = 1; a++ }).then(console.log)//.catch(console.log)
Promise.resolve(1).then(v => { const a = 1; a++ }).then(console.log).catch(console.log)

new Promise(function (resolve, reject) {
    resolve('1')
})
new Promise(function (resolve, reject) {
    reject('2')
})
new Promise(function (resolve, reject) {
    reject('3')
})


new Promise(function (resolve, reject) {
    setTimeout(v => resolve('1'), 1000)
}).then((...args) => console.log('1-1-then', args))
new Promise(function (resolve, reject) {
    setTimeout(v => reject('2'), 1000)
}).then((...args) => console.log('1-1-then', args))
new Promise(function (resolve, reject) {
    setTimeout(v => reject('3'), 1000)
}).then((...args) => console.log('1-1-then', args)).catch((...args) => console.log('1-2-catch', args))
new Promise(function (resolve, reject) {
    setTimeout(v => reject('4'), 1000)
}).then((...args) => console.log('1-1-then', args)).catch((...args) => console.log('1-2-catch', args)).then((...args) => console.log('1-3-then', args))




const promise1 = new Promise(function (resolve, reject) {
    setTimeout(() => {
        resolve(1000)
    }, 500)
})
const promise2 = new Promise(function (resolve, reject) {
    setTimeout(() => {
        reject(1001)
    }, 500)
})
const promise3 = new Promise(function (resolve, reject) {
    setTimeout(() => {
        reject(1002)
    }, 500)
})
setTimeout(() => promise1.then(console.log), 3000)
setTimeout(() => promise2.catch(console.log), 3000)
setTimeout(()=>promise3.catch(console.log), 100)

Answer 1

终于找到了人言：你不能在控制台使用它。你需要写在代码中，比如说 script 标签中。

必须是一个宏任务执行完成，没有 catch ，下个宏任务 catch 才会触发。同步、微任务都不行。

测试地址：http://jsrun.net/HI9Kp/edit

---

1. https://stackoverflow.com/que...
2. https://tc39.es/ecma262/#sec-...
3. https://www.ecma-internationa...

找到一些说法。但是还是没有解决问题

Answer 2

window.addEventListener("rejectionhandled", (ev) => {
    console.log("rejectionhandled ev.promise:", ev.promise);
    console.log("rejectionhandled ev.reason:", ev.reason);
});

window.addEventListener('unhandledrejection', event =>
{
    console.log('unhandledrejection: ', event.reason); // 打印"Hello, Fundebug!"
});

let p = Promise.reject("oops");

// setTimeout callback will be called in next event loop
setTimeout(() => {
    p.catch((err) => {console.log("handle rejection: " + err)});
}, 10);

将你的测试地址 setTimeout time 改到 10，才必触发 rejectionhandled。可能是 setTimeout 0 执行太快，错误在开始就被处理了，还未来的及抛出去，进而触发 unhandledrejection。

当一个Promise错误最初未被处理，但是稍后又得到了处理，则会触发rejectionhandled事件

参考：https://cloud.tencent.com/developer/article/1412389