console.history

A very small library to store all console logs in console.history.

Usage

Include console-history.js or console-history.min.js in your page or script before any console function gets called. All calls to console.log, console.info, console.warn, console.error and console.debug will be intercepted and stored after doing so. Including every parameter passed to those functions.

Getting Started

This library works in almost all browsers and on any NodeJS server.

Browser

You can download the latest release on GitHub, or use jsDelivr's CDN to get the latest version directly in your browser:

<script src="https://cdn.jsdelivr.net/gh/lesander/console.history@v1.5.1/console-history.min.js"></script>

See an example entry to the history array below. This example is from the test/test.js file.

{
  "type": "warn",
  "timestamp": "Thu, 01 Sep 2016 15:38:28 GMT",
  "arguments": {
    "0": "Something went wrong, but we're okay!"
  },
  "stack": {
    "0": "at inner (http://localhost:1337/test/test.js:6:11)",
    "1": "at outer (http://localhost:1337/test/test.js:2:3)",
    "2": "at http://localhost:1337/test/test.js:9:1"
  }
}

Server (NodeJS)

Fetch the latest version of console.history:

npm install console.history

require('console.history')
console.log('Hello World!')

At this point, the console.history array is populated with one entry:

[
  {
    type: 'log',
    timestamp: 'Thu, 16 Mar 2017 17:24:25 GMT',
    arguments: { '0': 'Hello World!' },
    stack: [
      'at Console.console._intercept (/.../console.history/test/node.js:4:11)',
      'at Object.<anonymous> (/.../console.history/test/node.js:6:9)',
      'at Module._compile (module.js:571:32)',
      'at Object.Module._extensions..js (module.js:580:10)',
      'at Module.load (module.js:488:32)',
      'at tryModuleLoad (module.js:447:12)',
      'at Function.Module._load (module.js:439:3)',
      'at Module.runMain (module.js:605:10)'
    ]
  }
]

Intercepting the log function

You can add your own middleware to console.history with the function console._intercept(type, args). This can prove useful when you need to access a new log entry before or after it gets logged and added to the history array. See an example below.

console._intercept = function (type, args) {

  if (type === 'error') {
    // send the error to your server or do something else..
  }

  // pass the log intent to the collector.
  console._collect(type, args)
}

Limitations

Every saved console log is stored locally in the array console.history. A page reload will erase all history, as the array is not permanently stored. You could use localStorage or sessionStorage for that.

How it works

This script is basically a man-in-the-middle for all console[log/info/warn/error/debug] functions. Every call gets intercepted, printed and added to the history array.

The code is not that hard to understand, see console-history.js with in-line comments explaining the code.

Contributing

If you'd like to contribute to console.history, or file a bug or feature request, please head over to the issue tracker or open a pull request.

Testing browser-side is as easy as running jekyll serve in the project's directory, navigating to localhost:4000/test in your browser and opening DevTools.

git clone https://github.com/lesander/console.history.git
cd console.history
jekyll serve

License

This software is open-sourced under the MIT License (see the LICENSE file for the full license). So within some limits, you can do with the code whatever you want. However, if you like and/or want to re-use it, I'd really appreciate a reference to this project page.

The software is provided as is. It might work as expected - or not. Just don't blame me.