html转markdown nodejs实现

 用到了jsdom库，直接现成处理html标签结构，只需要关心format格式化样式即可。

比较简易，待后续优化，目前只是短时间批量转换html文件。

const { JSDOM } = require('jsdom');

const getText = (htmlString) => {
    if (!htmlString) return "";
    if (typeof (htmlString) !== 'string') {
        htmlString = htmlString.textContent;
    }
    return htmlString.replaceAll(/\s+/g, ' ');
}
const format = {
    h1: (element) => {
        return `\n# ${getText(element)}\n`;
    },
    h2: (element) => {
        return `\n## ${getText(element)}\n`;
    },
    h3: (element) => {
        return `\n### ${getText(element)}\n`;
    },
    h4: (element) => {
        return `\n#### ${getText(element)}\n`;
    },
    h5: (element) => {
        return `\n##### ${getText(element)}\n`;
    },
    h6: (element) => {
        return `\n###### ${getText(element)}\n`;
    },
    code: (element) => {
        let className = element.getAttribute('class') || '';
        className = className.replace('language-', '');
        return '\n```' + className + "\n" + element.textContent + "\n```\n";
    },
    blockquote: (element) => {
        let result=reformat(element);
        let arr=result.split("\n\n");
        return "> "+arr.join("> ");
    },
    p: (element) => {
        return `\n${getText(reformat(element))}\n`;
    },
    strong: (element) => {
        return `**${getText(element)}**`
    },
    a: (element) => {
         return `[${getText(element)}](${element.getAttribute("href")})`
    },
    s: (element) => {
        return `~~${getText(element)}~~`
    },
    em: (element) => {
        return `*${getText(element)}*`
    },
    img: (element) => {
        return `![1](${element.getAttribute("src")})`;
    },
    ol: (element) => {
        let result = "\n";
        let index = 1;
        for (let child of element.childNodes) {
            if (child.tagName && child.tagName.toLowerCase() === 'li') {
                result += `${index++}. ${getText(child)}\n`;
            }
        }
        return result;
    },
    ul: (element) => {
        let result = "\n";
        for (let child of element.childNodes) {
            if (child.tagName && child.tagName.toLowerCase() === 'li') {
                result += `- ${getText(child)}\n`;
            }
        }
        return result;
    },
    table: (element) => {
        let result = "\n";
        let row = 0;
        const getTRString = (tr) => {
            let str = "|";
            if (tr) {
                for (let td of tr.childNodes) {
                    if (td.tagName && td.tagName.toLowerCase() === 'td') {
                        str += " " + getText(td) + "   |"
                    }
                }
            }
            if (str.length == 1) str = '| |'
            return str + "\n";
        }
        for (let child of element.childNodes) {
            if (child.tagName) {
                for (let tr of child.childNodes) {
                    if (tr.tagName && tr.tagName.toLowerCase() === 'tr') {
                        result += getTRString(tr);
                        row++;
                        if (row == 1) {//这个是markdown识别表格的标识  |---|---|--|----|--|  一般情况下宽度会自适应
                            result += "|"
                            for (let td of tr.childNodes) {
                                if (td.tagName && td.tagName.toLowerCase() === 'td') {
                                    result += "---|";
                                }
                            }
                            result += "\n";
                        }
                    }
                }
            }
        }
        return result;
    }
}
//二次格式化，如<p><strong>123</strong></p>  第一次格式化只会匹配到p，因此需要二次格式化处理内在元素
const reformat = (element) => {
    let result = "";
    for (let child of element.childNodes) {
        if (child.tagName && format[child.tagName.toLowerCase()]) {//拦截命中
            result += format[child.tagName.toLowerCase()](child);
        } else {//没有需要处理的标签，深入处理
            result += getText(child.textContent);
        }
    }
    return result;
}
const dp = (element) => {
    let markdownStringArray = [];
    for (let child of element.childNodes) {
        if (child.tagName) {
            let functionName = child.tagName.toLowerCase();//取出标签名称
            if (format[functionName]) {//拦截命中
                markdownStringArray.push(format[functionName](child));
            } else {//没有需要处理的标签，深入处理
                markdownStringArray = markdownStringArray.concat(dp(child));
            }
        }
    }
    return markdownStringArray;
}

exports.html_to_markdown = (htmlString) => {
    const dom = new JSDOM(htmlString);
    const body = dom.window.document.body;
    let arr = dp(body);
    return arr.join("");
}

使用方法

const markdownString= html_to_markdown(html);