Adds button to download all parts of an audio book from Overdrive.com

Download-Audio-Books.user.js

// ==UserScript==
// @name         Overdrive Audio Book Downloader
// @namespace    https://gist.github.com/MikeRawding
// @version      0.4
// @description  Adds a button to download all parts of an audio book from listen.overdrive.com
// @author       Mike Rawding
// @include      *listen.overdrive.com*
// @icon         https://www.overdrive.com/Content/img/icons/svg/overdrive-app-icon.svg
// @grant        none
// ==/UserScript==

(() => {
    'use strict';

    const GM_addStyle = (css) => {
        const style = document.getElementById("GM_addStyleBy8626") || (function() {
            const style = document.createElement('style');
            style.type = 'text/css';
            style.id = "GM_addStyleBy8626";
            document.head.appendChild(style);
            return style;
        })();
        const sheet = style.sheet;
        sheet.insertRule(css, (sheet.rules || sheet.cssRules || []).length);
    }

    GM_addStyle(".download-icon { width: 40px; padding-top: 20px; margin-left: 6px; height: 32px; cursor: pointer;}");

    let downloadButton = null

    const zeroPad = num => {
        if (num < 10) {
            return `0${num}`
        } else {
            return `${num}`
        }
    }

    const download = async ({ filename, url }) => {
        const response = await fetch(url)
        if (response.status !== 200) {
            throw new Error()
        }
        const blob = await response.blob()
        const downloadUrl = await URL.createObjectURL(blob)
        const link = document.createElement("a");
        link.href = downloadUrl;
        link.download = filename;
        document.body.appendChild(link);
        link.click();
        document.body.removeChild(link);
    }

    const downloadAll = () => {
        downloadButton.onclick = () => { }

        window.bData.spine.forEach((part, index) => {
            const url = `${window.location.origin}/${part.path}`
            const filename = `${window.bData.title.main}-Part${zeroPad(index + 1)}`
            download({ filename, url })
        })

        // Disable button for a moment so the user doesn't click twice
        setTimeout(() => {
            downloadButton.onclick = downloadAll
        }, 2_000)
    }

    const createButton = () => {
        const builderDiv = document.createElement('div')
        builderDiv.innerHTML =
            `
            <div title="Download All Parts" class="menu-bar-shortcut menu-bar-shortcut-speedo" touch-action="none" style="touch-action: none;">
                <svg viewBox="0 0 384 512" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" class="download-icon">
                    <g stroke="none" stroke-width="1" fill="none" fill-rule="evenodd">
                       <path d="M348.5 264l-148 148.5c-4.7 4.7-12.3 4.7-17 0L35.5 264c-4.7-4.7-4.7-12.3 0-17l7.1-7.1c4.7-4.7 12.3-4.7 17 0l115.4 116V44c0-6.6 5.4-12 12-12h10c6.6 0 12 5.4 12 12v311.9L324.4 240c4.7-4.7 12.3-4.7 17 0l7.1 7.1c4.7 4.6 4.7 12.2 0 16.9zM384 468v-8c0-6.6-5.4-12-12-12H12c-6.6 0-12 5.4-12 12v8c0 6.6 5.4 12 12 12h360c6.6 0 12-5.4 12-12z" stroke="#000000" stroke-width="3" stroke-linecap="round" class="icon-solid"></path>
                    </g>
                 </svg>
            </div>
        `.trim()
        downloadButton = builderDiv.firstChild
        downloadButton.onclick = downloadAll
        return downloadButton
    }

    /**
     * Adds download button
     * Might outrun the rest of the dom,
     * so keep retrying until the container is ready
     */
    const addButton = () => {
        const container = document.getElementsByClassName('nav-action-bar-right')
        if (container && container[0]) {
            container[0].appendChild(createButton())
        } else {
            setTimeout(addButton, 10)
        }
    }

    addButton()
})();

v0.2

1. Disable button while download in progress
2. Change button to use down arrow icon in same group as other sit icons

v0.3

1. Update favicon to correct URL

v0.4

1. Update selector to use new css class name on since overdrive.com has changed.