Promise.allSettled
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Promise.allSettled</title>
</head>
<body>
<script>
// 声明两个promise对象
const p1 = new Promise((resolve, reject) => {
setTimeout(() => {
resolve('商品数据 - 1')
}, 1000)
})
const p2 = new Promise((resolve, reject) => {
setTimeout(() => {
// resolve('商品数据 - 2')
reject('出错啦!')
}, 1000)
})
// Promise.allsettled：始终返回成功的promise，包括参数中的每个promise实例的状态、值，即得到每一个异步任务的结果
const result = Promise.allSettled([p1, p2])
console.log(result)
result.then(res => {
res.forEach(item => {
// 这样才能拿到 allsettled 中的数据
console.log(item.status)
console.log(item.value)
})
}).catch(rej =>
console.log(rej)
)
const res = Promise.all([p1, p2])
console.log(res)
res.then(res => {
res.forEach(item => {
console.log(item)
})
}).catch(rej =>
console.log(rej)
)
</script>
</body>
</html>
可选链操作符 --> ?.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>可选链操作符</title>
</head>
<body>
<script>
// ?.
function main(config) {
// const dbHost = config && config.db && config.db.host;
const dbHost = config?.db?.host;
console.log(dbHost);
}
main({
db: {
host: '192.168.1.100',
username: 'root'
},
cache: {
host: '192.168.1.200',
username: 'admin'
}
})
</script>
</body>
</html>