Html5VideoShortcut

YouTube-like keyboard shortcuts for HTML5 video.

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         Html5VideoShortcut
// @namespace    com.gmail.fujifruity.greasemonkey
// @version      0.1
// @description  YouTube-like keyboard shortcuts for HTML5 video.
// @author       fujifruity
// @match        *://*/*
// @grant        none
// @run-at       document-idle
// @license      MIT
// ==/UserScript==

{
    const Shortcut = (run, msg) => ({
        run: run,
        msg: msg
    })
    const getShortcut = (v /*video*/, key) =>
        // Play/Pause
         key == 'k' || key == ' ' ? Shortcut(() => v.paused ? v.play() : v.pause(), v.paused ? 'play' : 'pause') :
        // Seek
         key == 'j' ?               Shortcut(() => v.currentTime -= 10,     '-10s') :
         key == 'l' ?               Shortcut(() => v.currentTime += 10,     '+10s') :
         key == 'ArrowLeft' ?       Shortcut(() => v.currentTime -= 5,      '-5s') :
         key == 'ArrowRight' ?      Shortcut(() => v.currentTime += 5,      '+5s') :
         key == ',' ?               Shortcut(() => v.currentTime -= 0.0333, '') :
         key == '.' ?               Shortcut(() => v.currentTime += 0.0333, '') :
         '0' <= key && key <= '9' ? Shortcut(() => v.currentTime = parseInt(key) * v.duration / 10, key + '/10') :
        // Volume
         key == 'ArrowDown' ?       Shortcut(() => v.volume -= 0.1, parseInt(v.volume * 100) - 10 + '%') :
         key == 'ArrowUp' ?         Shortcut(() => v.volume += 0.1, parseInt(v.volume * 100) + 10 + '%') :
         key == 'm' ?               Shortcut(() => v.muted = !v.muted, v.muted ? 'unmute' : 'mute') :
        // Speed
         key == '<' && v.playbackRate >= 0.50 ? Shortcut(() => v.playbackRate -= 0.25, v.playbackRate - 0.25 + 'x') :
         key == '>' && v.playbackRate <= 1.75 ? Shortcut(() => v.playbackRate += 0.25, v.playbackRate + 0.25 + 'x') : null

    const modalTimeout = 400
    const modalId = 'fujifruity-Html5VideoShortcut'
    const showMsg = (v, msg) => {
        const modal = document.getElementById(modalId) ?? createModal()
        modal.innerText = msg
        const vrect = v.getBoundingClientRect()
        const top = vrect.y + vrect.height / 2 - modal.height / 2 //+ document.documentElement.scrollTop
        const left = vrect.x + vrect.width / 2 - modal.width / 2 //+ document.documentElement.scrollLeft
        modal.style.top = parseInt(top) + 'px'
        modal.style.left = parseInt(left) + 'px'
        modal.style.position = 'absolute'
        document.body.appendChild(modal)
        window.setTimeout(() => modal.remove(), modalTimeout)
    }
    const createModal = () => {
        const modal = document.createElement('div')
        modal.id = modalId
        modal.width = 80
        modal.height = 50
        modal.style.width = modal.width + 'px'
        modal.style.height = modal.height + 'px'
        modal.style.lineHeight = modal.height + 'px'
        modal.style.textAlign = 'center'
        modal.style.color = 'lightgray'
        modal.style.fontFamily = 'sans-serif'
        modal.style.backgroundColor = '#000000aa'
        return modal
    }

    window.addEventListener('keydown', event => {
        if (event.target.tagName != 'VIDEO') return
        if (event.ctrlKey || event.altKey || event.metaKey) return
        const v = event.target
        const shortcut = getShortcut(v, event.key)
        if (shortcut) {
            shortcut.run()
            if (shortcut.msg) showMsg(v, shortcut.msg)
            event.preventDefault()
        }
    })
}