diff --git a/src/common/csEventListener.js b/src/common/csEventListener.js
new file mode 100644
index 0000000..14b4295
--- /dev/null
+++ b/src/common/csEventListener.js
@@ -0,0 +1,43 @@
+// In order to pass i18n strings and settings values to the injected scripts,
+// which don't have access to the chrome.* APIs, we use event listeners.
+
+export function setUpListener() {
+  chrome.storage.sync.get(null, function(options) {
+    window.addEventListener('TWPT_sendRequest', evt => {
+      var request = evt.detail;
+      switch (request.data.action) {
+        case 'geti18nMessage':
+          var data = chrome.i18n.getMessage(
+              request.data.msg,
+              (Array.isArray(request.data.placeholders) ?
+                   request.data.placeholders :
+                   []));
+          break;
+
+        case 'getProfileIndicatorOptions':
+          var data = {
+            'indicatorDot': options.profileindicator,
+            'numPosts': options.profileindicatoralt
+          };
+          break;
+
+        case 'getNumPostMonths':
+          var data = options.profileindicatoralt_months;
+          break;
+
+        default:
+          var data = 'unknownAction';
+          console.warn('Unknown action ' + request.data.action + '.');
+          break;
+      }
+
+      var response = {
+        data,
+        requestId: request.id,
+        prefix: (request.prefix || 'TWPT'),
+      };
+
+      window.postMessage(response, '*');
+    });
+  });
+}