EH page swapper

Current: Use arrow key to flip pages in e-hentai.

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         EH page swapper
// @namespace    https://github.com/andylinpersonal/
// @version      0.1.3
// @description  Current: Use arrow key to flip pages in e-hentai.
// @require      http://code.jquery.com/jquery-latest.js
// @author       Andy Lin
// @run-at       document-start
// @match        https://exhentai.org/*
// @match        https://e-hentai.org/*
// @grant        unsafeWindow
// ==/UserScript==

(function() {
  'use strict';
  /**
   * Logging messages to console.
   * @param {String} modeStr - log mode: can be 'error', 'warning', 'log', and other
   * @param {String} inStr - What to display.
   * @returns {void}
   */
  function logger(modeStr, inStr) {
    if (modeStr === 'error') {
      console.error('EHFlipper: Error: ' + inStr);
    } else if (modeStr === 'warning') {
      console.warn('EHFlipper: Warning: ' + inStr);
    } else if (modeStr === 'log') {
      console.log('EHFlipper: Message: ' + inStr);
    } else {
      console.log('EHFlipper: ' + modeStr + ': ' + inStr);
    }
  }

  /**
   * Check operation mode from url format
   * @param {String} url - URL of current page.
   * @returns {Object} Mode object.
   */
  function modeChecker(url) {
    /**
     * Get current page
     * @param {String} url - URL of current page.
     * @param {RegExp} patternOfPage - Pattern of page string
     * @param {int} startOfNum - Start offset of page number
     * @returns {int} Current page.
     */
    function pageChecker(url, patternOfPage) {
      var found = url.match(patternOfPage);
      if (found) {
        found = found[1];
      } else {
        return 0;
      }
      var out = Number(found);
      if (isNaN(out)) return 0;
      return out;
    }

    if (url.match(/\/g\//)) {
      return {
        'type': 'gallery',
        'page': (pageChecker(url, /(?:p=)([0-9]*)/, 2) + 1)
      };
    } else if (url.match(/\/s\//)) {
      return {
        'type': 'show',
        'page': (pageChecker(url, /[0-9a-zA-Z]{1,1}-(?:([0-9]{1,}))/, 2))
      };
    } else {
      return {
        'type': 'main',
        'page': (pageChecker(url, /(?:(?:page=)|(?:\/))([0-9]{1,})/) + 1)
      };
    }
  }

  /**
   * Event handler of keydown event
   * @param {KeyboardEvent} e - KeyboardEvent
   * @returns {void}
   */
  function go(e) {
    /**
     * Go~~
     * @param {Object} mode - Where are you?
     * @param {String} action - Previous or next page?
     * @returns {void}
     */
    function switchPage(mode, action) {
      switch (mode.type) {
        case 'main':
          var tmpMain = $('.ptt tr')[0].children;
          if (action === 'next') {
            tmpMain[tmpMain.length - 1].click();
            return;
          } else if (action === 'previous') {
            tmpMain[0].click();
            return;
          }
          break;
        case 'show':
          if (action === 'next') {
            $('#i2 #next')[0].click();
            return;
          } else if (action === 'previous') {
            $('#i2 #prev')[0].click();
            return;
          }
          break;
        case 'gallery':
          var tmpGal = $('.ptt tr')[0].children;
          if (action === 'next') {
            tmpGal[tmpGal.length - 1].click();
            return;
          } else if (action === 'previous') {
            tmpGal[0].click();
            return;
          }
          break;
        default:
          logger('error', 'Unknown mode: ' + mode.type);
          break;
      }
      logger('error', 'Unknown action: ' + action);
    }
    var url = unsafeWindow.document.location.href;
    var mode = modeChecker(url);
    switch (e.key) {
      case 'ArrowLeft':
        logger('log', e.key + ' is pressed.');
        switchPage(mode, 'previous');
        break;
      case 'ArrowRight':
        logger('log', e.key + ' is pressed.');
        switchPage(mode, 'next');
        break;
      default:
        logger(
          'log', 'Unknown key "' +
          e.key +
          '" with keyCode "' +
          e.keyCode +
          '"is pressed.');
        break;
    }
  }

  var url = unsafeWindow.document.location.href;
  var mode = modeChecker(url);
  logger('Current location', url);
  logger('Current page', mode.page);
  // Register event handler to <body>
  // Because keypress event will ignore arrow key, I use keydown instead.
  $('body').keydown(go);
})();