js_eval

NAME

js_eval - evaluate JavaScript in the hosting page, synchronously

SYNOPSIS

string js_eval(string code);

DESCRIPTION

Evaluates `code` as JavaScript in the context of the page (or node
process) hosting the WASM driver and returns the result as a string:
primitives are stringified, objects are JSON-encoded, undefined/null
become "". A thrown JavaScript exception is returned as the string
"JS error: ..." — it never unwinds into the driver.

Only available on the WebAssembly build (guard LPC code with
`#ifdef __PACKAGE_JSBRIDGE__`).

EXAMPLES

```c
write(js_eval("navigator.userAgent"));
int width = to_int(js_eval("window.innerWidth"));
```

SEE ALSO

js_call(3)

NOTE

A page can disable eval entirely with a Content-Security-Policy; use
js_call(3) with page-registered handlers for anything structural.