Promise 忽略简单的同步操作

Question

在承诺中，我想为从一个类（在循环中）创建的几个对象的属性分配一个值，但是在执行函数并执行 .then(() => console.log(r)) 事情时，r 没有修改为承诺承诺的内容我会的。

这里：

function assignSentenceImageDescription () {
    return new Promise((resolve, reject) =>
    {
        assigningWordsPartOFSpeech().then((r) => {

                JSON.parse(r).sentences.forEach((sentence) => {
                        let adjectiveBeforeNoun = [];
                        let sentenceImageDescription = [];
                        sentence.words.forEach((wordInSentence) => {
                            try {
                                if (wordInSentence.partOfSpeech[0].wordtype === "n.") {
                                    let imageDescription = adjectiveBeforeNoun.join('') + wordInSentence.partOfSpeech[0].word;
                                    sentenceImageDescription.push(imageDescription)
                                    adjectiveBeforeNoun = [];
                                } else if (wordInSentence.partOfSpeech[0].wordtype === "superl.") {
                                    adjectiveBeforeNoun.push(wordInSentence.partOfSpeech[0].word + " ")
                                }
                            } catch (e) {
                                console.log("===NOT IN DICTIONARY===")
                            }
                        })
                        sentence.imageDescription = sentenceImageDescription;
                    }
                )
                resolve(r);
            }
        );
    }
    );
}

在线上

sentence.imageDescription = sentenceImageDescription;

我尝试为每个重复的句子分配图像描述，但是当我这样做时

assignSentenceImageDescription().then(r => console.log(r));

r 对象仍然没有将其每个 sentences 的 imageDescription 属性修改为数组 sentenceImageDescription 所具有的值，而这正是 assignSentenceImageDescription() 函数的目的。

Answer 1

按如下方式重构您的代码：

注意：您不需要 Promise 构造函数，因为 assigningWordsPartOFSpeech 返回一个您可以使用（并返回）的 Promise

设置sentences = JSON.parse(r).sentences;

现在你可以像你已经做的那样遍历句子，然后在 .then 中简单地 return sentences - 你就完成了

function assignSentenceImageDescription() {
    return assigningWordsPartOFSpeech().then((r) => {
        const data = JSON.parse(r);
        data.sentences.forEach((sentence) => {
            let adjectiveBeforeNoun = [];
            let sentenceImageDescription = [];
            sentence.words.forEach((wordInSentence) => {
                try {
                    if (wordInSentence.partOfSpeech[0].wordtype === "n.") {
                        let imageDescription = adjectiveBeforeNoun.join('') + wordInSentence.partOfSpeech[0].word;
                        sentenceImageDescription.push(imageDescription)
                        adjectiveBeforeNoun = [];
                    } else if (wordInSentence.partOfSpeech[0].wordtype === "superl.") {
                        adjectiveBeforeNoun.push(wordInSentence.partOfSpeech[0].word + " ")
                    }
                } catch (e) {
                    console.log("===NOT IN DICTIONARY===")
                }
            })
            sentence.imageDescription = sentenceImageDescription;
        });
        return data;
    });
}