localStorage Assertions

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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:

// 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

​How Capture Works

​Planning for Multi-Step Tests

​JSON Values

​What You Can Query

​Example Assertions

​Example Extractions

​Example If/Else