2.4 KiB
console_error_panic_hook
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
With this panic hook installed you will see the panic message
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.