封装方法优雅处理async/await 报错

一般使用try/catch 处理 async/await 报错，

const fetchData = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve('fetch data is me')
        }, 1000)
    })
}

(async () => {
    try {
        const data = await fetchData()
        console.log('data is ->', data)
    } catch(err) {
        console.log('err is ->', err)
    }
})()

单个处理的时候感觉还行，当我们需要大量处理这种逻辑的时候，try/catch 就显得比较臃肿了，我们先看下多个的处理情况

const fetchDataA = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve('fetch data is A')
        }, 1000)
    })
}

const fetchDataB = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve('fetch data is B')
        }, 1000)
    })
}

const fetchDataC = () => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            resolve('fetch data is C')
        }, 1000)
    })
}

(async () => {
    try {
        const dataA = await fetchDataA()
        console.log('dataA is ->', dataA)
    } catch(err) {
        console.log('err is ->', err)
    }

    try {
        const dataB = await fetchDataB()
        console.log('dataB is ->', dataB)
    } catch(err) {
        console.log('err is ->', err)
    }

    try {
        const dataC = await fetchDataC()
        console.log('dataC is ->', dataC)
    } catch(err) {
        console.log('err is ->', err)
    }
})()

或者写在一个里面

// ... 这里 fetch 函数省略

(async () => {
    try {
        const dataA = await fetchDataA()
        console.log('dataA is ->', dataA)
        const dataB = await fetchDataB()
        console.log('dataB is ->', dataB)
        const dataC = await fetchDataC()
        console.log('dataC is ->', dataC)
    } catch(err) {
        console.log('err is ->', err)
        // 难道要定义 err 类型，然后判断吗？？
        /**
         * if (err.type === 'dataA') {
         *  console.log('dataA err is', err)
         * }
         * ......
         * */
    }
})()

方法1 try/catch 多写了一堆 方法2 判断逻辑写了一堆 都不是咱想要的效果，此时就应该想办法封装一个统一了逻辑去处理了， 通过数组，以及promise的resolve,reject 区分 返回内容，然后根据返回数组内容做处理

    //js 写法
     const awaitWrap = (promise) => {
        return promise
            .then(data => [null, data])
            .catch(err => [err, null])
   }
   
   //ts 写法
   function awaitWrap<T, U = any>(promise: Promise<T>): Promise<[U | null, T | null]> {
        return promise
            .then<[null, T]>((data: T) => [null, data])
            .catch<[U, null]>(err => [err, null])
    }

使用

(async () => {
    const fetchData = () => {
        return new Promise((resolve, reject) => {
            setTimeout(() => {
                resolve('fetch data is me')
            }, 1000)
        })
    }

    // 抽离成公共方法
    const awaitWrap = (promise) => {
        return promise
            .then(data => [null, data])
            .catch(err => [err, null])
    }

    const [err, data] = await awaitWrap(fetchData())
    console.log('err', err)
    console.log('data', data)
    // err null
    // data fetch data is me
})()