寻求帮助修复损坏的承诺链

Question

这是承诺链。我觉得它看起来不错，但它并没有像我想要的那样工作。我已经看过了，一切似乎都井井有条。作为新手，我是否只是在 .then 的每次新迭代中重复 poem？我正在前往.catch，因为它会打印出“出了点问题”，我希望得到任何建议！

let poem = 'But I must explain to you how all this mistaken idea of denouncing pleasure and praising pain was born and I will give you a complete account of the system, and expound the actual teachings of the great explorer'

const poemJudge = (poem) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            if(poem.length > 25){
                console.log('We need to review this poem further');
                resolve(poem);
            } else {
                reject('woah what? way too elementary');
            }
        }, generateRandomDelay());
    });
};

const keepThinking = (resolvedPoem) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            if(resolvedPoem.length < 45) {
                console.log('terse, but we must deliberate further');
                resolve(resolvedPoem);
            } else {
                reject('seriously? the poem is way too long!');
            }
        }, generateRandomDelay())

    });
};

const KeepOnThinking = (secondResolvedPoem) => {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
            if(secondResolvedPoem < 40 && secondResolvedPoem > 30) {
                console.log('Nailed it')
                resolve(secondResolvedPoem);
            } else {
                reject('you are top 50 at least')
            }
        }, generateRandomDelay());
    });
};


poemJudge(poem)
.then((resolvedPoem) => {
    return keepThinking(resolvedPoem);
})
.then((secondResolvedPoem) => {
    return keepOnThinking(secondResolvedPoem);
})
.then(() => {
    console.log('you have completed the poem challenge');
})
.catch(() => {
    console.log('something went wrong');
});

Answer 1

假设您在代码中定义了方法 generateRandomDelay。

当你调用reject() 时，一个promise 失败并且它被捕获在一个.catch 块中。 在这个例子中，这首诗的长度是 > 25 和

1. poemJudge 解决了它
2. keepThinking 拒绝它
3. 您的 catch 块捕获了拒绝。

您可以通过记录您在 catch 块中收到的消息 (err) 来确认这一点：

poemJudge(poem)
.then((resolvedPoem) => {
    return keepThinking(resolvedPoem);
})
.then((secondResolvedPoem) => {
    return keepOnThinking(secondResolvedPoem);
})
.then(() => {
    console.log('you have completed the poem challenge');
})
.catch(err => {
    console.log(err);
});

您的控制台将打印：

我们需要进一步复习这首诗

真的吗？这首诗太长了！