原文链接: MDN
| Promise |
|
| 状态 |
pending, fulfilled, rejected |
| 作用 |
代理对象（值），解决异步回调 |
| 特点 |
链式调用，成功(onfulfilled)和失败(onrejected)绑定相应处理方法 |
| 方法 |
优、缺点 |
| Promise.all(iterable) |
处理异步队列成功会返回一个promise对象（值为数组，顺序与队列一致）。队列中任一task出错将触发promise失败，仅返回出错task的错误信息 |
| Promise.race(iterable) |
返回最早返回值的task信息(不论成功失败) |
| Promise.reject(reason) |
|
|
|
let successQuery = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve('successQuery')
}, 1000)
})
}
let errorQuery = () => {
return new Promise((resolve, reject) => {
reject('errorQuery')
})
}
Promise.all([successQuery(), errorQuery()]).then(data => {
console.log('success: ', data)
}).catch(error => {
console.log('error: ', error)
})
//error: errorQuery
//Promise.race(iterable)
//@(1)
let successQuery = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve('successQuery')
}, 3000)
})
}
let errorQuery = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
reject('errorQuery')
}, 2000)
})
}
Promise.race([successQuery(), errorQuery()]).then(data => {
console.log('success: ', data)
}).catch(error => {
console.log('error: ', error)
})
// error: errorQuery
//@(2)
let successQuery = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve('successQuery')
}, 1000)
})
}
let errorQuery = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
reject('errorQuery')
}, 2000)
})
}
Promise.race([successQuery(), errorQuery()]).then(data => {
console.log('success: ', data)
}).catch(error => {
console.log('error: ', error)
})
// success: successQuery
