diff.pug

doctype html
head
    meta(charset='utf-8')
    meta(name="viewport" content="width=device-width")
    title diff
    script(src='https://cdn.jsdelivr.net/gh/google/diff-match-patch@master/javascript/diff_match_patch.js')
    style.
        #app {
            background-color: white;
            color: black;
            position: absolute;
            left: 0; right: 0;
            top: 0; bottom: 0;
        }
        .row {
            display: flex;
        }
        .col {
            flex: 1;
        }
body
    main#app.row
        textarea#left.col
        textarea#right.col
        #result.col
    script.
        var l = document.querySelector('#left')
        var r = document.querySelector('#right')
        var a = document.querySelector('#result')
        l.oninput = r.oninput = function() {
            var diff = new diff_match_patch()
            var d = diff.diff_main(l.value, r.value)
            diff.diff_cleanupSemantic(d)
            var html = diff.diff_prettyHtml(d)
            a.innerHTML = html
        }

make-pug.js

const path = require('path');
const pug = require('pug');
const fs = require('fs-extra');
const minify = require('html-minifier').minify;

async function work(file) {
    const exist = await fs.pathExists(file);
    if (!exist) return;
    const text = await fs.readFile(file);
    const rawhtml = pug.render(text);
    const html = minify(rawhtml, {
        caseSensitive: false,
        collapseBooleanAttributes: true,
        collapseInlineTagWhitespace: false,
        collapseWhitespace: true,
        conservativeCollapse: false,
        decodeEntities: true,
        html5: true,
        includeAutoGeneratedTags: false,
        keepClosingSlash: false,
        minifyCSS: true,
        minifyJS: true,
        preserveLineBreaks: false,
        preventAttributesEscaping: false,
        processConditionalComments: true,
        processScripts: ['text/html'],
        removeAttributeQuotes: true,
        removeComments: true,
        removeEmptyAttributes: true,
        removeEmptyElements: false,
        removeOptionalTags: true,
        removeRedundantAttributes: true,
        removeScriptTypeAttributes: true,
        removeStyleLinkTypeAttributes: true,
        removeTagWhitespace: true,
        sortAttributes: true,
        sortClassName: true,
        trimCustomFragments: true,
        useShortDoctype: true,
    });
    const target = path.join(
        path.dirname(file),
        path.basename(file, path.extname(file)) + '.html'
    );
    await fs.writeFile(target, html);
    console.info(file, '->', target, 'ok');
}

async function main() {
    try {
        const files = await fs.readdir('.');
        const pugs = files.filter(e => path.extname(e) === '.pug');
        await Promise.all(pugs.map(work));
    } catch (err) {
        console.error(err.msg);
        console.error(err.filename, err.line, err.column);
    }
}

main();