Add model and add event listeners

src/model/Path.ts

@@ -0,0 +1,26 @@
+
+type PathElement = (string | number)
+
+export class Path {
+  private arr: PathElement[]
+
+  constructor(arr?: PathElement[]) {
+    this.arr = arr || []
+  }
+
+  last(): PathElement {
+    return this.arr[this.arr.length - 1]
+  }
+
+  pop(): Path {
+    return new Path(this.arr.slice(0, -1))
+  }
+
+  push(element: PathElement): Path {
+    return new Path([...this.arr, element])
+  }
+
+  copy(): Path {
+    return new Path([...this.arr])
+  }
+}