dynamically generate version field for manifest.json from package.json

src/manifests/chrome.json

@@ -1,7 +1,5 @@
 {
-  "manifest_version": 2,
   "name": "Sample WebExtension",
-  "version": "0.0.1",
   "author": "abhijithvijayan",
   "short_name": "Sample Name",
   "description": "Sample description",
@@ -10,6 +8,7 @@
     "persistent": false,
     "scripts": ["js/background.js"]
   },
+  "manifest_version": 2,
   "minimum_chrome_version": "49",
   "permissions": ["tabs", "storage", "http://*/*", "https://*/*"],
   "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'",

src/manifests/firefox.json

@@ -1,7 +1,5 @@
 {
-  "manifest_version": 2,
   "name": "Sample WebExtension",
-  "version": "0.0.1",
   "author": "abhijithvijayan",
   "short_name": "Sample Name",
   "description": "Sample description",
@@ -9,6 +7,7 @@
   "background": {
     "scripts": ["js/background.js"]
   },
+  "manifest_version": 2,
   "permissions": ["tabs", "storage", "http://*/*", "https://*/*"],
   "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'",
   "icons": {

src/manifests/opera.json

@@ -1,7 +1,5 @@
 {
-  "manifest_version": 2,
   "name": "Sample WebExtension",
-  "version": "0.0.1",
   "developer": {
     "name": "abhijithvijayan"
   },
@@ -12,6 +10,7 @@
     "persistent": false,
     "scripts": ["js/background.js"]
   },
+  "manifest_version": 2,
   "minimum_opera_version": "36",
   "permissions": ["tabs", "storage", "http://*/*", "https://*/*"],
   "content_security_policy": "script-src 'self' 'unsafe-eval'; object-src 'self'",

webpack.config.js

@@ -35,7 +35,20 @@ module.exports = {
         }),
         new CopyWebpackPlugin([
             { from: 'src/assets', to: 'assets' },
-            { from: `src/manifests/${process.env.TARGET}.json`, to: 'manifest.json' },
+            {
+                from: `src/manifests/${process.env.TARGET}.json`,
+                // expose and write the allowed env vars on the compiled bundle
+                transform(content, path) {
+                    // generates the manifest file using the package.json informations
+                    return Buffer.from(
+                        JSON.stringify({
+                            version: process.env.npm_package_version,
+                            ...JSON.parse(content.toString()),
+                        })
+                    );
+                },
+                to: 'manifest.json',
+            },
         ]),
         new HtmlWebpackPlugin({
             template: 'src/options.html',