books_view

www/data/javascript/ms_basic.js

@@ -0,0 +1,32 @@
+function findParent(el, selector) {
+    let retval = null;
+    while (el) {
+        if (el.matches(selector)) {
+            retval = el;
+            break
+        }
+        el = el.parentElement;
+    }
+    return retval;
+}
+
+function findChild(el, selector) {
+    for (let i = 0; i < el.children.length; i++) {
+        if (el.children[i].matches(selector)) { return el.children[i]; }
+        let rec = findChild(el.children[i], selector);
+        if (rec !== null) return rec;
+    }
+    return null;
+}
+
+function imgcarousel_move(source, delta) {
+    let carousel = findParent(source, ".imgcarousel_parent");
+    let index    = parseInt(carousel.getAttribute('data-imgcarousel-index'));
+    let images   = JSON.parse(carousel.getAttribute('data-imgcarousel-images'));
+    let content  = findChild(carousel, '.imgcarousel_content');
+
+    index = (index + delta +  images.length) % images.length;
+
+    carousel.setAttribute('data-imgcarousel-index', index);
+    content.setAttribute('style', 'background-image: url(' + images[index] + ');');
+}