From 6ab44e9aeaeeab87290b461b039efa2bf534608a Mon Sep 17 00:00:00 2001
From: Martin Packman <martin.packman@visual-meaning.com>
Date: Sat, 3 Apr 2021 17:57:11 +0100
Subject: [PATCH] Allow private class members to be mangled

Openlayers classes use an underscore suffix convention to mark class
members as private. These are undocumented implementation details and
presumably unsafe for code outside the class to rely on.

Allowing javascript minimisation to change these names gives 5% bundle
size reduction to the library.
---
 config/webpack-config-legacy-build.js | 12 ++++++++++++
 examples/webpack/config.js            |  4 ++++
 2 files changed, 16 insertions(+)

diff --git a/config/webpack-config-legacy-build.js b/config/webpack-config-legacy-build.js
index a7fb3a7977..92d32bfa00 100644
--- a/config/webpack-config-legacy-build.js
+++ b/config/webpack-config-legacy-build.js
@@ -1,4 +1,6 @@
 const path = require('path');
+const TerserPlugin = require('terser-webpack-plugin');
+
 module.exports = {
   entry: './build/index.js',
   devtool: 'source-map',
@@ -30,6 +32,16 @@ module.exports = {
       ol: path.resolve('./build/ol'),
     },
   },
+  optimization: {
+    minimizer: [
+      new TerserPlugin({
+        terserOptions: {
+          // Mangle private members convention with underscore suffix
+          mangle: {properties: {regex: /_$/}},
+        },
+      }),
+    ],
+  },
   output: {
     path: path.resolve('./build/legacy'),
     filename: 'ol.js',
diff --git a/examples/webpack/config.js b/examples/webpack/config.js
index 7f7692715f..e3a1108a51 100644
--- a/examples/webpack/config.js
+++ b/examples/webpack/config.js
@@ -61,6 +61,10 @@ module.exports = {
         // Do not minify examples that inject code into workers
         exclude: [/(color-manipulation|region-growing|raster)\.js/],
         extractComments: false,
+        terserOptions: {
+          // Mangle private members convention with underscore suffix
+          mangle: {properties: {regex: /_$/}},
+        },
       }),
     ],
     runtimeChunk: {