wasm-logger

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

screenshot

The log entry's format is:

$LOG_LEVEL $LINE_NUMBER:$FILE_PATH
$MESSAGE

In v0.1.4, the default Config will put the message on the same line as other info (see more). If you want them on a separate line as the screenshot above, you must config like this:

wasm_logger::init(
    wasm_logger::Config::new(log::Level::Debug)
        .message_on_new_line()
);

Usage

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

Cargo.toml

[dependencies]
log = "0.4"
wasm-logger = "0.1.4"

Initialize wasm-logger when your app start:

wasm_logger::init(wasm_logger::Config::new(log::Level::Debug));

// 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.

License

MIT or Apache-2.0