A set of macros for interfacing with `console.log`, `console.error` and other browser console APIs when targeting Wasm.
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Crates.io version docs.rs docs

weblog is a crate that defines a set of macros for calling console.log(), console.error() and other members of the browser's console API when targeting Wasm.


  • Supports web-sys and stdweb backends with an identical public API
  • Support for variadic arguments on all calls
  • No stringification before sending to the browser - log entire objects and use the full introspective debugging power of the browser console.


A simple example.

console_log!("Hello world!");

Passing multiple arguments is fine too.

console_log!("Foo", "bar", "baz");

All of the common browser log levels are supported.

console_debug!("Just testing...");
console_warn!("...but then...");
console_error!("...something bad happened.");

It's possible to send more than just strings or &strs:


When using web-sys crate the macros accept any value that implements the Into<JsValue> trait. See JsValue for more details.

No stringification is performed on the Rust side - so objects will be fully introspectable in the browser's console!


# Defaults to web-sys
weblog = "0.3.0"

# For stdweb:
weblog = { version = "0.3.0", default-features = false, features = ["std_web"] }

See the documentation for usage examples.

The crate currently exposes the following macros:

  • console_assert!
  • console_clear!
  • console_count!
  • console_count_reset!
  • console_debug!
  • console_dir!
  • console_dirxml!
  • console_error!
  • console_exception!
  • console_info!
  • console_log!
  • console_table!
  • console_time!
  • console_time_end!
  • console_time_stamp!
  • console_trace!
  • console_warn!


Licensed under MIT or Apache-2.