Save widget to standalone HTML file (#199)

.gitignore

@@ -1,3 +1,5 @@
+*.html
+*.zip
 *.geojson
 *.geojson.zip
 *.arrow

build.mjs

@@ -1,15 +1,15 @@
 // build.js
 import esbuild from "esbuild";
-// import { wasmLoader } from "esbuild-plugin-wasm";
 
 esbuild.build({
-  entryPoints: [
-    "./src/index.tsx",
-  ],
+  entryPoints: ["./src/index.tsx"],
   bundle: true,
   minify: true,
   target: ["es2020"],
   outdir: "lonboard/static/",
-  // plugins: [wasmLoader()],
   format: "esm",
+  // Ref https://github.com/manzt/anywidget/issues/369#issuecomment-1792376003
+  define: {
+    "define.amd": "false",
+  },
 });

lonboard/_map.py

@@ -1,10 +1,12 @@
 from __future__ import annotations
 
 from pathlib import Path
+from typing import Union
 
 import anywidget
 import ipywidgets
 import traitlets
+from ipywidgets.embed import embed_minimal_html
 
 from lonboard._layer import BaseLayer
 from lonboard._viewport import compute_view
@@ -92,6 +94,14 @@ class Map(anywidget.AnyWidget):
     - Default: `True`
     """
 
+    def to_html(self, filename: Union[str, Path]) -> None:
+        """Save the current map as a standalone HTML file.
+
+        Args:
+            filename: where to save the generated HTML file.
+        """
+        embed_minimal_html(filename, views=[self], drop_defaults=False)
+
     @traitlets.default("_initial_view_state")
     def _default_initial_view_state(self):
         tables = [layer.table for layer in self.layers]