Console API

The Console API provides functionality to allow developers to perform debugging tasks, such as logging messages or the values of variables at set points in your code, or timing how long an operation takes to complete.

Note: This feature is available in Web Workers

Concepts and usage

The Console API started as a largely proprietary API, with different browsers implementing it, albeit it in inconsistent ways. The Console API spec was created to define consistent behavior, and all modern browsers eventually settled on implementing this behavior — although some implementations still have their own additional proprietary functions. Find out about these at:

Usage is very simple — the console object — available via window.console, or WorkerGlobalScope.console in workers; accessible using just console — contains many methods that you can call to perform rudimentary debugging tasks, generally focused around logging various values to the browser's Web Console.

By far the most commonly-used method is console.log, which is used to log the current value contained inside a specific variable.

Interfaces

console
Provides rudimentary debugging functionality, including logging, stack traces, timers, and counters.

Examples

let myString = 'Hello world';

// Output "Hello world" to the console
console.log(myString)

See the console reference page for more examples.

Specifications

Specification
Console Standard (Console)
# console-namespace

Browser compatibility

BCD tables only load in the browser

See also

  • Tools
  • Web Console — how the Web Console in Firefox handles console API calls
  • Remote debugging — how to see console output when the debugging target is a mobile device