javascript - 如何避免在 IF 语句中嵌套 promise

Question

我知道我们不应该在函数中嵌套 promise ，而且我的所有函数根本没有任何嵌套，但是我不知道如何避免在我的一个函数的 if-else 语句中嵌套 promise 。

        const staffRef = db.collection("staff").doc(uid)
        return staffRef.get()
            .then((doc) => {
                if (doc.exists) {
                    return staffRef.delete()
                        .then(() => {
                            console.log("Employee ", uid, " profile has been deleted in staff collection")
                            return null
                        })
                } else {
                    console.log("Employee ", uid, " had no dependencies")
                    return null
                }
            })

我不认为这是嵌套，但我在部署时仍然收到警告。我应该如何重组此代码以避免嵌套警告？我知道那里有一些类似的答案，但没有一个有 if else 语句

Answer 1

您可以抛出错误并捕获它，如下所示:

    const staffRef = db.collection("staff").doc(uid)
    return staffRef.get()
        .then((doc) => {
            if (doc.exists) {
                return staffRef.delete();
            } else {
                console.log("Employee ", uid, " had no dependencies")
                throw new Error("Employee " + uid + " had no dependencies");
            }
        })
        .then(() => {
            console.log("Employee ", uid, " profile has been deleted in staff collection");
            return null;
        })
        .catch(error => {
            console.log(error);
            return null;
        });