Check for localStorage support

src/lib/request.spec.ts

@@ -1,6 +1,6 @@
 /* eslint-disable functional/no-let */
 /* eslint-disable functional/immutable-data */
-import { sendEvent } from './request';
+import { checkLocalStorageSupport, sendEvent } from './request';
 import { PlausibleOptions } from './tracker';
 
 const getXhrMockClass = () => ({
@@ -111,6 +111,15 @@ describe('sendEvent', () => {
     sendEvent('myEvent', { ...defaultData, trackLocalhost: true });
     expect(xmr).toHaveBeenCalled();
   });
+  test('can determine if localStorage is supported in an inlined data:uri iframe', () => {
+    const fauxWindow = {} as Window;
+    const hasLocalStorageSupport = checkLocalStorageSupport(fauxWindow);
+    expect(hasLocalStorageSupport).toBeFalsy();
+  });
+  test('can determine if localStorage is supported in a true DOM environment with a window object', () => {
+    const hasLocalStorageSupport = checkLocalStorageSupport();
+    expect(hasLocalStorageSupport).toBeTruthy();
+  });
   test('does not send if "plausible_ignore" is set to "true" in localStorage', () => {
     window.localStorage.setItem('plausible_ignore', 'true');
     expect(xmr).not.toHaveBeenCalled();

src/lib/request.ts

@@ -25,6 +25,30 @@ export type EventOptions = {
   readonly props?: { readonly [propName: string]: string };
 };
 
+export const checkLocalStorageSupport = (
+  g?: Window | typeof globalThis | (Window & typeof globalThis)
+): boolean => {
+  try {
+    if (g) {
+      const supported =
+        'localStorage' in g &&
+        g['localStorage'] !== null &&
+        g['localStorage'].setItem('plausible_test', `1`) === undefined;
+      g['localStorage'].removeItem('plausible_test');
+      return supported;
+    } else {
+      const supported =
+        'localStorage' in window &&
+        window['localStorage'] !== null &&
+        window['localStorage'].setItem('plausible_test', `1`) === undefined;
+      window['localStorage'].removeItem('plausible_test');
+      return supported;
+    }
+  } catch (_e) {
+    return false;
+  }
+};
+
 /**
  * @internal
  * Sends an event to Plausible's API
@@ -48,8 +72,11 @@ export function sendEvent(
     );
   }
 
+  const hasLocalStorageSupport = checkLocalStorageSupport();
   const shouldIgnoreCurrentBrowser =
+    hasLocalStorageSupport &&
     localStorage.getItem('plausible_ignore') === 'true';
+
   if (shouldIgnoreCurrentBrowser) {
     return console.warn(
       '[Plausible] Ignoring event because "plausible_ignore" is set to "true" in localStorage'