GitHub - rustwasm/console_error_panic_hook: A panic hook for wasm32-unknown-unknown that logs panics with console.error (original) (raw)

console_error_panic_hook

Build Status

This crate lets you debug panics on wasm32-unknown-unknown by providing a panic hook that forwards panic messages toconsole.error.

When an error is reported with console.error, browser devtools and node.js will typically capture a stack trace and display it with the logged error message.

Without console_error_panic_hook you just get something like RuntimeError: Unreachable executed

Browser:Console without panic hook

Node:Node console without panic hook

With this panic hook installed you will see the panic message

Browser:Console with panic hook set up

Node:Node console with panic hook set up

Usage

There are two ways to install this panic hook.

First, you can set the hook yourself by calling std::panic::set_hook in some initialization function:

extern crate console_error_panic_hook; use std::panic;

fn my_init_function() { panic::set_hook(Box::new(console_error_panic_hook::hook));

// ...

}

Alternatively, use set_once on some common code path to ensure thatset_hook is called, but only the one time. Under the hood, this usesstd::sync::Once.

extern crate console_error_panic_hook;

struct MyBigThing;

impl MyBigThing { pub fn new() -> MyBigThing { console_error_panic_hook::set_once();

    MyBigThing
}

}

Error.stackTraceLimit

Many browsers only capture the top 10 frames of a stack trace. In rust programs this is less likely to be enough. To see more frames, you can set the non-standard value Error.stackTraceLimit. For more information see the MDN Web Docs or v8 docs.