已关闭，该问题为opinion-based，目前不接受回答。
**想改进这个问题吗？**更新问题，以便editing this post可以用事实和引用来回答。

7天前关闭
Improve this question
我这里的用例：

• 如果资源立即可用，则返回它
• 如果一个资源还不可用，那么显示一个模态或加载指示器，然后等待它准备好
• 模态逻辑必须与promise/request逻辑解耦

有更好的设计模式吗？

let twoStagePromise = (state: boolean): Promise<{ ready: boolean, wait: Promise<any>; }> => {
    return new Promise((resolve, reject) => {
        try {
            if (state) {
                resolve({
                    ready: true,
                    wait: new Promise((resolve, reject) => {
                        resolve([1, 2, 3]);
                    })
                });
            } else {
                resolve({
                    ready: false,
                    wait: new Promise((resolve, reject) => {
                        setTimeout(() => { resolve([1, 2, 3]); }, 1000);
                    })
                });
            }
        } catch (e) {
            reject(e);
        }
    });
};

twoStagePromise(false).then((data) => {
    if (!data.ready) {
        console.log('loading...');
    }
    return data.wait;
}).then((result) => {
    console.log("recieved result", result);
}).catch((error) => {
    console.log("try-catch failed or inner promise failed")
});

在阅读了一些注解后，我简化了代码：

let twoStagePromise = (state: boolean): Promise<number[] | Promise<number[]>> => {
    return new Promise((resolve, reject) => {
        try {
            if (state) {
                resolve([1, 2, 3]);
            } else {
                resolve(new Promise((resolve) => setTimeout(() => { resolve([1,2,3])  }, 1000)))
            }
        } catch (e) {
            reject(e);
        }
    });
};

twoStagePromise(false).then((dataOrPromise) => {
    if (dataOrPromise instanceof Promise) {
        console.log('loading...');
    }
    return dataOrPromise // continue the promise chain by returning the promise or data
}).then((result) => {
    console.log("recieved result", result);
}).catch((error) => {
    console.log("try-catch failed or inner promise failed", error)
});