javbus.waterfall

Infinite scroll @ javbus.com
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// ==UserScript==
// @name        javbus.waterfall
// @description Infinite scroll @ javbus.com
// @namespace   https://github.com/FlandreDaisuki
// @include     *://*.javbus.*/*
// @version     2019.10.16
// @grant       none
// @license     MIT
// @noframes
// ==/UserScript==

/* global jQuery */

// Configuration
const FETCH_TRIG = '400px';
const COL_CNT = 4;
const IS_DENSE = false;

// Utilities
const $ = jQuery;

const global = {
  pageCount: 0,
  itemCount: 0,
  parent: $('#waterfall'),
  columnParents: Array(COL_CNT).fill().map(() => $('<div class="column">')),
  columnHeights: Array(COL_CNT).fill(0),
  nextURL: location.href,
  locked: false,
  baseURI: location.origin,
  selector: {
    next: 'a#next',
    item: '.item',
  },
};

const addStyle = (styleStr) => {
  $('head').append(`<style>${styleStr}</style>`);
};

const getNextURL = (href) => {
  const a = document.createElement('a');
  a.href = href;
  return `${global.baseURI}${a.pathname}${a.search}`;
};

const fetchURL = async(url) => {
  console.log(`fetchUrl = ${url}`);

  const resp = await fetch(url, { credentials: 'same-origin' });
  const html = await resp.text();
  const doc = new DOMParser().parseFromString(html, 'text/html');

  const $doc = $(doc);

  const href = $doc.find(global.selector.next).attr('href');
  const nextURL = href ? getNextURL(href) : null;
  const elems = $doc.find(global.selector.item);

  return {
    nextURL,
    elems,
  };
};

const intersectionObserverOptions = {
  rootMargin: `0px 0px ${FETCH_TRIG} 0px`,
  threshold: Array(5).fill().map((_, index, arr) => index / arr.length),
};

const intersectionObserver = new IntersectionObserver(async() => {
  if (global.locked) { return; }
  global.locked = true;
  const { nextURL, elems } = await fetchURL(global.nextURL);

  if (global.pageCount === 0) {
    global.parent.empty().append(global.columnParents);
  }

  const items = elems.toArray();
  if (global.pageCount > 0 && location.pathname.includes('/star/')) {
    items.shift();
  }

  for (const item of items) {
    if (IS_DENSE) {
      const idx = global.columnHeights.indexOf(Math.min(...global.columnHeights));
      global.columnParents[idx].append(item);
      global.columnHeights[idx] += item.clientHeight;
    } else {
      global.columnParents[global.itemCount % COL_CNT].append(item);
    }

    global.itemCount += 1;
  }

  // finally
  global.pageCount += 1;
  global.nextURL = nextURL;
  global.locked = false;

  if (!global.nextURL) {
    console.info('The End');
    global.parent.after($('<h1 id="end">The End</h1>'));
    intersectionObserver.disconnect();
    return;
  }
}, intersectionObserverOptions);

intersectionObserver.observe($('footer').get(0));

const SHARED_STYLE = `
#waterfall {
  height: initial !important;
  width: initial !important;
  display: flex;
}
#waterfall .item.item {
  position: relative !important;
  top: initial !important;
  left: initial !important;
  float: none;
}
h1#end {
  text-align: center;
}`;

const GRID_STYLE = `
#waterfall > .column {
  flex: 1;
}
#waterfall .movie-box,
#waterfall .avatar-box {
  width: initial !important;
  display: flex;
}
#waterfall .movie-box .photo-frame {
  overflow: visible;
}`;

const DENSE_STYLE = `
#waterfall {
  justify-content: center;
}
#waterfall > .column {
  display: flex;
  flex-direction: column;
}
#waterfall .item.item {
  position: relative !important;
  top: initial !important;
  left: initial !important;
  float: none;
}`;

addStyle(SHARED_STYLE);
addStyle(IS_DENSE ? DENSE_STYLE : GRID_STYLE);