javascript - 如何等待函数中的获取函数？

Question

下面是我的代码

export const redirectDomain: any = (lang, ctx, res) => {
    let redirectString;

    const getData = async () => {
        try {
            const response = await fetch('https://www.example.com');
            const data= await response.json();

            return data;
        } catch (error) {
            console.log('[ERROR]');
        }
    };

    const data = getData();
    const redirectUrl = data.split(',');

    return redirectUrl;
};

为什么输出会显示错误

Cannot read property 'split' of undefined

Answer 1

async 函数之外的事情不会等待 promise 得到解决。因此，当您拆分时，data 仍然是undefined。所以这是解决方案之一......

export const redirectDomain: any = async (lang, ctx, res) => {
    let redirectString;

    const getData = async () => {
        try {
            const response = await fetch('https://www.example.com');
            const data = await response.json();

            return data;
        } catch (error) {
            console.log('[ERROR]');
        }
    };

    const data = await getData();
    const redirectUrl = data.split(',');

    return redirectUrl;
};

另一个解决方案(我更喜欢这个):

export const redirectDomain: any = async (lang, ctx, res) => {
    let redirectString;
    let data;
    try {
        const response = await fetch('https://www.example.com');
        data = await response.json();
    } catch (error) {
        console.log('[ERROR]');
    }

    const redirectUrl = data.split(',');

    return redirectUrl;
};

此外，如果我要编写这段代码(让我弄清楚我将如何处理错误 xD):

export const redirectDomain: any = (lang, ctx, resp) =>
    fetch("https://www.example.com")
    .then(res => res.json())
    .then(data => Promise.resolve(data.split(",")));

我想说的是，有时 promises 看起来比 async/await 更好。