add meun

src/layers.js

@@ -2,15 +2,25 @@ let id = 0;
 export default class Layers {
   constructor(art) {
     this.art = art;
+    this.add = this.add.bind(this);
+    this.art.option.layers.forEach(this.add);
   }
 
   add(option) {
     const { refs } = this.art;
     id++;
+
     refs.$layers.insertAdjacentHTML('beforeend', `
-      <div data-layer-index="${id}" class="art-layer art-layer-${option.name}" style="z-index: ${option.index || id}">
-        ${option.html}
+      <div
+        data-art-layer-id="${id}"
+        class="art-layer art-layer-${option.name || id}"
+        style="z-index: ${option.index || id}"
+      >
+        ${option.html || ''}
       </div>
     `);
+
+    const $layer = refs.$layers.querySelector(`[data-art-layer-id="${id}"]`);
+    option.callback && option.callback($layer);
   }
 }