A logger that routes messages to the browser's console.
use log::Level;
fn main() {
console_log::init_with_level(Level::Debug);
info!("It works!");
// ...
}Rust's log levels map to the browser's console log in the following way.
| Rust | Web Console |
|---|---|
trace!() |
console.debug() |
debug!() |
console.log() |
info!() |
console.info() |
warn!() |
console.warn() |
error!() |
console.error() |
The "color" feature adds styling to the log messages.
Cargo.toml
console_log = { version = "1", features = ["color"] }The styled log messages will be rendered as follows:
Twiggy reports this library adding about 180Kb to the size of a minimal wasm binary in a debug build. If you want to avoid this, mark the library as optional and conditionally initialize it in your code for non-release builds.
Cargo.toml
[dependencies]
cfg-if = "0.1"
log = "0.4"
console_log = { version = "1", optional = true }
[features]
default = ["console_log"]lib.rs
use wasm_bindgen::prelude::*;
use cfg_if::cfg_if;
cfg_if! {
if #[cfg(feature = "console_log")] {
fn init_log() {
use log::Level;
console_log::init_with_level(Level::Trace).expect("error initializing log");
}
} else {
fn init_log() {}
}
}
#[wasm_bindgen]
pub fn main() {
init_log();
// ...
}The file and line number information associated with the log messages reports
locations from the shims generated by wasm-bindgen, not the location of the
logger call.
This project is licensed under either of
- Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.
wasm-loggerwasm-bindgen-console-loggerfern(use withconsole_log::log)