Implement a simple content script injector

lib/renderer/content-scripts-injector.js

@@ -0,0 +1,35 @@
+const preferences = process.getRenderProcessPreferences()
+if (!preferences || preferences.length == 0) return
+
+const {webFrame} = require('electron')
+
+// Check whether pattern matches.
+// https://developer.chrome.com/extensions/match_patterns
+const matchesPattern = function (pattern) {
+  if (pattern === '<all_urls>')
+    return true
+
+  const regexp = new RegExp('^' + pattern.replace(/\*/g, '.*') + '$')
+  return location.href.match(regexp)
+}
+
+// Run injected scripts.
+// https://developer.chrome.com/extensions/content_scripts
+const injectContentScript = function (script) {
+  for (const match of script.matches) {
+    if (!matchesPattern(match)) return
+  }
+
+  for (const js of script.js) {
+    if (script.runAt === 'document_start') {
+      webFrame.executeJavaScript(String(js))
+    }
+  }
+}
+
+// Read the renderer process preferences.
+for (const pref of preferences) {
+  if (pref.contentScripts) {
+    pref.contentScripts.forEach(injectContentScript)
+  }
+}