static/js/app.js

const imageInput = document.querySelector("#imageInput");
const imageUrlInput = document.querySelector("#imageUrlInput");
const previewCard = document.querySelector("#previewCard");
const imagePreview = document.querySelector("#imagePreview");

function showPreview(src) {
  if (!previewCard || !imagePreview || !src) return;
  imagePreview.src = src;
  previewCard.hidden = false;
}

if (imageInput) {
  imageInput.addEventListener("change", () => {
    const file = imageInput.files && imageInput.files[0];
    if (!file) return;
    showPreview(URL.createObjectURL(file));
    if (imageUrlInput) imageUrlInput.value = "";
  });
}

if (imageUrlInput) {
  imageUrlInput.addEventListener("input", () => {
    const value = imageUrlInput.value.trim();
    if (!value) return;
    showPreview(value);
    if (imageInput) imageInput.value = "";
  });
}