Read a JavaScript value from the browser by property path.
Walks a strict property path — NO expression evaluation, NO function
calls, NO arbitrary code. Accepts identifiers, integer indices in
brackets, and double-quoted string keys in brackets.
Use this to read runtime state that isn't visible in the DOM:
- Framework hydration: window.__NEXT_DATA__.props.pageProps
- Redux/Zustand/etc stores (if exposed on window): window.__STORE__._currentState
- Feature flags stashed on globals: window.APP.flags
- Nested config: window["site-config"].features[0]
EXPLORATION MODE: pass mode="keys" to get Object.keys() at the path
instead of the value. Start with path="window" to discover globals,
then drill in. This is how to find exposed state without guessing:
get_js_value(path="window", mode="keys")
-> ["document", "__NEXT_DATA__", "store", ...]
get_js_value(path="window.store", mode="keys")
-> ["_currentState", "subscribe", "dispatch", ...]
get_js_value(path="window.store._currentState")
-> the actual state object
LIMITATIONS (intentional — security):
- Cannot call functions. "store.getState()" fails. Expose the value
as a readable property instead, e.g. window.__STORE__.state.
- No arithmetic, comparisons, or expressions.
- Path must start with an identifier and walk down via dots/brackets.
Responses are cycle-safe, depth-capped, and size-capped. DOM nodes
and React fiber trees are summarized rather than traversed.
Args:
key: Session key
secret: Session secret from create_session
path: Property path, e.g. "window.__NEXT_DATA__.props.pageProps"
or 'window["site-config"].features[0]' or 'window.arr[0].name'
mode: "value" (default) returns the serialized value; "keys" returns Object.keys() at the path
max_depth: Max traversal depth when serializing (default 6, capped at 10)
max_bytes: Max serialized size in bytes (default 20000, capped at 100000)
Returns:
{path, type, value, truncated, size_bytes} in value mode
{path, mode, type, keys} in keys mode
{error: "..."} on bad path / function / failure
Requires a connected browser session and middleware v0.9.6+ (older
middleware works — the relay doesn't care; the browser needs agent.js
from relay.sncro.net which auto-updates).
Connector