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Alex Mingoia

A Brief History of JavaScript’s console

You probably use it every day, yet there’s no standard implementation. It was introduced 10 years ago, but despite its age and widespread adoption console is not part of ECMAScript.

Where did it come from? What did people do before console.log?

Older versions of Firefox, Opera, and Internet Explorer circa 2000 had introduced a JavaScript “Console” that kept a log of errors and sometimes included a debugger for setting breakpoints. You could evaluate JS in these consoles but had no way of writing your own messages to the log.

Mozilla JavaScript Console - ©

Mozilla JavaScript Console - ©

Writing to that console was the inspiration for console.log. Without it, developers used a combination of window.alerts and tools that wrote log messages to hidden DOM elements or attributes. One such tool was fvlogger released in 2005 by David F. Miller of A List Apart. Other tools with an interface similar to Apache log4j appeared in 2005, including log4js by Tim Down and JSLogger by Dan Allen.

console appears to have been first introduced in its current form in 2006 by Firebug, a web development plugin for Firefox. Firebug provided an enhanced web console capable of debugging, profiling, and DOM inspection. Similar plugins for other browsers appeared shortly after. These third-party development consoles put pressure on browsers to incorporate their features. Eventually, a console object was introduced in Internet Explorer 8, Opera 9.5, and Safari 3 (not confirmed).

Today still there is no standardized implementation of console object and its methods. Even console.log behaves slightly different across browsers. It’s grown beyond the Firebug implementation, with methods for tables, timers, and stack traces. The Developer Tools Working Group has begun a draft console standard to improve parity between implementations. With widespread implementation across browsers and node.js, it looks like console is here to stay.

Posted on September 30, 2015
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