#console #panic #error #hook #logs #panic-hook

console_error_panic_hook

A panic hook for wasm32-unknown-unknown that logs panics to console.error

8 releases

Uses old Rust 2015

0.1.7 Oct 11, 2021
0.1.6 Feb 15, 2019
0.1.5 Sep 6, 2018
0.1.4 Aug 14, 2018
0.1.1 May 23, 2018

#3 in WebAssembly

Download history 39308/week @ 2021-09-26 39718/week @ 2021-10-03 69369/week @ 2021-10-10 74652/week @ 2021-10-17 63806/week @ 2021-10-24 64727/week @ 2021-10-31 61181/week @ 2021-11-07 60423/week @ 2021-11-14 59548/week @ 2021-11-21 60244/week @ 2021-11-28 45286/week @ 2021-12-05 48591/week @ 2021-12-12 36397/week @ 2021-12-19 33961/week @ 2021-12-26 44880/week @ 2022-01-02 47298/week @ 2022-01-09

167,126 downloads per month
Used in 886 crates (160 directly)

Apache-2.0/MIT

510KB

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 to console.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 that set_hook is called, but only the one time. Under the hood, this uses std::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.

Dependencies

~0.7–1.3MB
~27K SLoC