first commit

services/web/frontend/js/features/fallback-image/index.js

@@ -0,0 +1,16 @@
+function loadingFailed(imgEl) {
+  return imgEl.complete && imgEl.naturalWidth === 0
+}
+
+document.querySelectorAll('[data-ol-fallback-image]').forEach(imgEl => {
+  function showFallback() {
+    imgEl.src = imgEl.getAttribute('data-ol-fallback-image')
+  }
+  if (loadingFailed(imgEl)) {
+    // The image loading failed before the sprinkle ran.
+    showFallback()
+  } else {
+    // The image loading might fail in the future.
+    imgEl.addEventListener('error', showFallback)
+  }
+})