Add storage testers

snippets/isLocalStorageEnabled.md

@@ -0,0 +1,26 @@
+---
+title: isLocalStorageEnabled
+tags: browser,intermediate
+---
+
+Checks if `localStorage` is enabled.
+
+- Use a `try...catch` block to return `true` if all operations complete successfully, `false` otherwise.
+- Use `Storage.setItem()` and `Storage.removeItem()` to test storing and deleting a value in `window.localStorage`.
+
+```js
+const isLocalStorageEnabled = () => {
+  try {
+    const key = `__storage__test`;
+    window.localStorage.setItem(key, null);
+    window.localStorage.removeItem(key);
+    return true;
+  } catch (e) {
+    return false;
+  }
+};
+```
+
+```js
+isLocalStorageEnabled(); // true, if localStorage is accessible
+```

snippets/isSessionStorageEnabled.md

@@ -0,0 +1,26 @@
+---
+title: isSessionStorageEnabled
+tags: browser,intermediate
+---
+
+Checks if `sessionStorage` is enabled.
+
+- Use a `try...catch` block to return `true` if all operations complete successfully, `false` otherwise.
+- Use `Storage.setItem()` and `Storage.removeItem()` to test storing and deleting a value in `window.sessionStorage`.
+
+```js
+const isSessionStorageEnabled = () => {
+  try {
+    const key = `__storage__test`;
+    window.sessionStorage.setItem(key, null);
+    window.sessionStorage.removeItem(key);
+    return true;
+  } catch (e) {
+    return false;
+  }
+};
+```
+
+```js
+isSessionStorageEnabled(); // true, if sessionStorage is accessible
+```