geekVideoSeek.user.js

// ==UserScript==
// @name         geekVideoSeek
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @match        https://u.geekbang.org/lesson/*
// @grant        none
// ==/UserScript==

(function() {
    'use strict';

    // Your code here...
    const pat = /((?:\d{1,2}\W*[:：]\ ?\W*)?\d{1,2}\W*[:：]\ ?\W*\d{1,2})\W*-/g

    function waitForResult(func, interval = 1000, maxTrials = 10) {
        return new Promise((resolve, reject) => {
            let trial = 1
            function wait() {
                const res = func()
                if (res) {
                    resolve(res)
                    return
                }
                trial++
                if (trial >= maxTrials) {
                    reject(new Error('max trials exceeded'))
                    return
                }
                setTimeout(wait, interval)
            }
            wait()
        })
    }

    function toSeconds(text) {
        return text.split(/[:：]/).reduce((acc, val) => acc * 60 + Number(val), 0)
    }

    function seekVideo(seconds) {
        const video = document.querySelector('video')
        video.currentTime = seconds
    }

    function createButton(text) {
        const res = document.createElement('button')
        res.innerText = text
        res.setAttribute('style', [
            'background: none;',
            'border: none;',
            'padding: 0;',
            'color: #069;',
            'text-decoration: underline;',
            'cursor: pointer;',
            'display: block;',
            ].join(' '))
        return res
    }

    waitForResult(() => {
        const res = [...document.querySelectorAll('li, p')]
            .filter(e => e.innerText.match(pat) !== null)
        if (res.length > 0) return res
    })
    .then(res => {
        for (const e of res) {
            const str = e.innerText
            e.innerText = ''
            const matches = [...str.matchAll(pat)]
            const startIndices = matches.map(m => m.index).concat(str.length)
            for (let i = 0; i < matches.length; i++) {
                const seconds = toSeconds(matches[i][1])
                const caption = str.substring(startIndices[i], startIndices[i + 1])
                const btn = createButton(caption)
                btn.onclick = () => seekVideo(seconds)
                e.appendChild(btn)
            }
        }
    })
    .catch(err => {
        console.error(err)
    })
})();