#wasm #front-end #logger #console #log


A logger that sends a message with its Rust source’s line and filename to the browser console

4 releases

✓ Uses Rust 2018 edition

new 0.1.3 Apr 13, 2019
0.1.2 Feb 15, 2019
0.1.1 Jan 11, 2019
0.1.0 Oct 4, 2018

#68 in WebAssembly

36 downloads per month


110 lines


A logger that sends a message with its Rust source's line and filename to the browser console.


The log entry's format is:



Note: For more information about how to use loggers in Rust, see log.


log = "0.4"
wasm-logger = "0.1.3"

Initialize wasm-logger when your app start:


// Logging
log::info!("Some info");
log::error!("Error message");

Log for a specific module only

You can provide a path prefix:

wasm_logger::init(wasm_logger::Config::with_prefix(log::Level::Debug, "some::module"));

then, wasm-logger only logs message from some::module

Mapping from log to console's methods

log::error!, log::warn! and log::info! call theirs equivalent methods of the browser console. The console.trace method outputs some extra trace from the generated JS glue code which we don't want. Therefore, we choose to map:

  • log::debug! to console.log
  • log::trace! to console.debug.

Note for Chromium/Chrome users

Chromium/Chrome filters out console.debug (execute by log::trace!) by default. You must check the Verbose filter in your browser console to see trace entries.


MIT or Apache-2.0


~35K SLoC