Give devs more options for dynamically setting publicPath

assets/build/config.js

@@ -31,15 +31,27 @@ const config = mergeWithConcat({
 config.watch.push(`${path.basename(config.paths.assets)}/${config.copy}`);
 config.watch = uniq(config.watch);
 
-Object.keys(config.entry).forEach(id =>
-  config.entry[id].unshift(path.join(__dirname, 'public-path.js')));
-
 module.exports = mergeWithConcat(config, {
   env: Object.assign({ production: isProduction, development: !isProduction }, argv.env),
   publicPath: `${config.publicPath}/${path.basename(config.paths.dist)}/`,
   manifest: {},
 });
 
-if (config.enabled.watcher && !process.env.WEBPACK_PUBLIC_PATH) {
-  process.env.WEBPACK_PUBLIC_PATH = config.publicPath;
+/**
+ * If your publicPath differs between environments, but you know it at compile time,
+ * then set SAGE_DIST_PATH as an environment variable before compiling.
+ * Example:
+ *   SAGE_DIST_PATH=/wp-content/themes/sage/dist yarn build:production
+ */
+if (process.env.SAGE_DIST_PATH) {
+  module.exports.publicPath = process.env.SAGE_DIST_PATH;
 }
+
+/**
+ * If you don't know your publicPath at compile time, then uncomment the lines
+ * below and use WordPress's wp_localize_script() to set SAGE_DIST_PATH global.
+ * Example:
+ *   wp_localize_script('sage/main.js', 'SAGE_DIST_PATH', get_theme_file_uri('dist/'))
+ */
+// Object.keys(module.exports.entry).forEach(id =>
+//   module.exports.entry[id].unshift(path.join(__dirname, 'public-path.js')));