[mod] infinite_scroll as preference

* oscar theme: code from searx/plugins/infinite_scroll.py
* simple theme: new implementation

Co-authored-by: Markus Heiser <markus.heiser@darmarIT.de>

1 files changed, 88 insertions, 0 deletions

diff --git a/searx/static/themes/simple/src/js/main/infinite_scroll.js b/searx/static/themes/simple/src/js/main/infinite_scroll.js
new file mode 100644
index 000000000..b900e66e2
--- /dev/null
+++ b/searx/static/themes/simple/src/js/main/infinite_scroll.js
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+/* global searxng */
+
+searxng.ready(function () {
+  'use strict';
+
+  searxng.infinite_scroll_supported = (
+    'IntersectionObserver' in window &&
+    'IntersectionObserverEntry' in window &&
+    'intersectionRatio' in window.IntersectionObserverEntry.prototype);
+
+  if (searxng.endpoint !== 'results') {
+    return;
+  }
+
+  if (!searxng.infinite_scroll_supported) {
+    console.log('IntersectionObserver not supported');
+    return;
+  }
+
+  let d = document;
+  var onlyImages = d.getElementById('results').classList.contains('only_template_images');
+
+  function newLoadSpinner () {
+    var loader = d.createElement('div');
+    loader.classList.add('loader');
+    return loader;
+  }
+
+  function replaceChildrenWith (element, children) {
+    element.textContent = '';
+    children.forEach(child => element.appendChild(child));
+  }
+
+  function loadNextPage (callback) {
+    var form = d.querySelector('#pagination form.next_page');
+    if (!form) {
+      return
+    }
+    replaceChildrenWith(d.querySelector('#pagination'), [ newLoadSpinner() ]);
+    var formData = new FormData(form);
+    searxng.http('POST', d.querySelector('#search').getAttribute('action'), formData).then(
+      function (response) {
+        var nextPageDoc = new DOMParser().parseFromString(response, 'text/html');
+        var articleList = nextPageDoc.querySelectorAll('#urls article');
+        var paginationElement = nextPageDoc.querySelector('#pagination');
+        d.querySelector('#pagination').remove();
+        if (articleList.length > 0 && !onlyImages) {
+          // do not add <hr> element when there are only images
+          d.querySelector('#urls').appendChild(d.createElement('hr'));
+        }
+        articleList.forEach(articleElement => {
+          d.querySelector('#urls').appendChild(articleElement);
+        });
+        if (paginationElement) {
+          d.querySelector('#results').appendChild(paginationElement);
+          callback();
+        }
+      }
+    ).catch(
+      function (err) {
+        console.log(err);
+        var e = d.createElement('div');
+        e.textContent = searxng.translations.error_loading_next_page;
+        e.classList.add('dialog-error');
+        e.setAttribute('role', 'alert');
+        replaceChildrenWith(d.querySelector('#pagination'), [ e ]);
+      }
+    )
+  }
+
+  if (searxng.infinite_scroll && searxng.infinite_scroll_supported) {
+    const intersectionObserveOptions = {
+      rootMargin: "20rem",
+    };
+    const observedSelector = 'article.result:last-child';
+    const observer = new IntersectionObserver(entries => {
+      const paginationEntry = entries[0];
+      if (paginationEntry.isIntersecting) {
+        observer.unobserve(paginationEntry.target);
+        loadNextPage(() => observer.observe(d.querySelector(observedSelector), intersectionObserveOptions));
+      }
+    });
+    observer.observe(d.querySelector(observedSelector), intersectionObserveOptions);
+  }
+
+});