> ## Documentation Index
> Fetch the complete documentation index at: https://www.testmuai.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# localStorage Assertions

> Verify key-value pairs stored in the browser localStorage during test execution: auth tokens, feature flags, cached data.

***

<Note>
  **Using Claude Code, Cursor, or another coding agent?** Paste this into your prompt to run cross-browser and real-device tests, debug sessions, and wire up CI on the TestMu AI cloud:

  ```
  Read https://www.testmuai.com/support/docs/SKILL.md to set up TestMu AI (formerly LambdaTest) cloud testing.
  ```
</Note>

localStorage assertions let you verify data stored in the browser's `window.localStorage`: check key existence, values, and item counts.

## How Capture Works

localStorage is captured as a **point-in-time snapshot** when the checkpoint triggers:

* **On-demand capture**: localStorage is read from the current page at the moment the assertion runs
* **Current state only**: You see exactly what's in localStorage right now
* **Domain-scoped**: localStorage is per-origin (protocol + domain + port). You only see data for the current page's origin
* **String values**: All localStorage values are strings. If the application stores JSON objects, they're stored as JSON strings

### Planning for Multi-Step Tests

Because localStorage is captured at assertion time:

* Assert on localStorage while you're **on the page** that set the values. Navigating to a different domain means a different localStorage
* If values are needed later, extract and store them before navigating away
* localStorage persists across steps (unlike network/console) as long as you stay on the same origin

### JSON Values

Applications often store structured data in localStorage as JSON strings:

```javascript theme={null}
// Application code
localStorage.setItem("user_prefs", JSON.stringify({theme: "dark", lang: "en"}));
```

In assertions, the value is the raw JSON string. You can parse it to check individual fields:

```
Assert: the "theme" field in the user_prefs localStorage item is "dark"
```

KaneAI will parse the JSON and drill into the value automatically.

## What You Can Query

| Method             | Returns         | Description              |
| ------------------ | --------------- | ------------------------ |
| `storage.all()`    | dict            | All key-value pairs      |
| `storage.get(key)` | string or None  | Value for a specific key |
| `storage.keys()`   | list of strings | All key names            |
| `storage.has(key)` | bool            | Whether a key exists     |

## Example Assertions

```
Assert: auth_token exists in localStorage
Assert: the theme preference in localStorage is "dark"
Assert: localStorage has fewer than 10 items
Assert: the user_id value in localStorage is not empty
```

## Example Extractions

```
Store all localStorage items
Extract the auth_token from localStorage
Store the user preferences from localStorage
Get all localStorage keys
```

## Example If/Else

```
If localStorage has "onboarding_complete" then show dashboard, else start onboarding
```