answer for promise paging exercise

paging.js

//ref https://www.v2ex.com/t/346533#r_4122841
const api = (num) => {
    const allNum = 3 + parseInt(7 * Math.random());//你不知到总页数的
    const quality = 0.15;//接口质量指数

    return new Promise((resolve, reject) => {
        setTimeout(_=>{//超时逻辑
            reject({
                code: 'CODE_TIMEOUT',
                msg: 'timeout'
            })
        }, 500);

        //你不知道api到底会出什么错误,甚至可能直接永远没有结果
        let problem = 0;
        if(Math.random() < quality) {
            problem = 10 * Math.random();
            if(problem < 2) {
                return;
            }
        }
        setTimeout(() => {
            if(problem > 0) {
                if(problem < 5) {
                    return reject(new Error('some logic error'));
                }
                if(problem < 8) {
                    return reject({
                        randomStuff: Math.random()
                    });
                }
                return reject(null);
            }

            //返回结果模拟的有点小问题
            if (num <= allNum) {
                resolve([0,0,num]);//列表应该是多个值
            } else {
                resolve([]);//我说的API是返回空列表表示结束，不是false
            }
        }, 10)
    })
}


const getList = (num = 1) => {
    return api(num).then(null/*注意传null的行为*/, error => Promise.reject({/*封装错误*/
            currentPage: num,
            error
        })
    );
}

const getWholeList = (num = 1, list = []) => {
    return getList(num).then(res => {
        if(res.length == 0) {
            return list;
        }

        return getWholeList(num + 1, [...list, ...res]);
    }/*注意因为错误已经被getList封装了，此处无需处理*/);
}

getWholeList().then(res => {
    console.log('完成', res);
}, e => {/*你的版本里的getWholeList并没有把错误体现到最终结果*/
    console.error('失败', e);
})