CODEWITHSUNDEEP
javascriptseleniumfirebug
adam goucher
adam goucher

Reputation: 1936

reading the firebug console in javascript

I'm looking for a way to read the most recent command that was logged to the firebug console.

For example, I could have something that does

console.debug('The most current request URI is /sweatsocks');

And then another piece of (pseudo)code could then

if (mostRecentConsoleEntry().endsWith('/sweatsocks')) {
  // do some stuff
}

The context being the debug statement would be in the code under test, and the console checking would be done inside a selenium script. This would let me observe information buried deep in js functions as well as stuff that is built at runtime.

Upvotes: 4

Views: 4896

Answers (5)

Timo Tijhof
Timo Tijhof

Reputation: 10269

Here's a more elaborate version I put together:

/**
 * Console log with memory
 *
 * Example:
 *
 *     console.log(1);
 *     console.history[0]; // [1]
 *
 *     console.log(123, 456);
 *     console.history.slice(-1)[0]; // [123, 456]
 *
 *     console.log('third');
 *     // Setting the limit immediately trims the array,
 *     // just like .length (but removes from start instead of end).
 *     console.history.limit = 2;
 *     console.history[0]; // [123, 456], the [1] has been removed
 *
 * @author Timo Tijhof, 2012
 */
console.log = (function () {
    var log  = console.log,
        limit = 10,
        history = [],
        slice = history.slice;

    function update() {
        if (history.length > limit) {
            // Trim the array leaving only the last N entries
            console.history.splice(0, console.history.length - limit);
        }
    }

    if (console.history !== undefined) {
        return log;
    }

    Object.defineProperty(history, 'limit', {
        get: function () { return limit; },
        set: function (val) {
            limit = val;
            update();
        }
    });

    console.history = history;

    return function () {
        history.push(slice.call(arguments));
        update();
        return log.apply(console, arguments);
    };

}());

Upvotes: 0

nickf
nickf

Reputation: 546005

You could overwrite the console.log function to add whatever extra functionality you need.

var oldLog = console.log;
var lastLog;
console.log = function () {
    // do whatever you need to do here: store the logs into a different variable, etc
    // eg:
    lastLog = arguments;

    // then call the regular log command
    oldLog.apply(console, arguments);
};

This won't be the most bulletproof solution, since console allows printf style syntax:

console.log("%d + %d = %s", 1, 3, "four");

...but it's probably a start for you.

Upvotes: 5

Rimian
Rimian

Reputation: 38418

You might wanna implement a queue. Expanding on Devin's answer: (something like this)

var window.log = [];

logger function(msg) {
  var log_length = 10;
  console.log(msg);
  window.log.push(msg);
  if(window.log.length > log_length) {
    window.log.shift()
  }
}

See:
How do you implement a Stack and a Queue in JavaScript?
http://aymanh.com/9-javascript-tips-you-may-not-know#string-concatenation-vs-arrayjoin

Upvotes: -1

alex
alex

Reputation: 490153

Could you rewrite the console.log(), and append all logs to an array? Then fire up the original console.log() and repeat what it's doing to get your debug output on the console?

Upvotes: 1

Devin Rhode
Devin Rhode

Reputation: 25267

Don't try and override console.debug, implement a function that does console.debug plus what you need.

var debugCalls = [ ];
function myDebug(errorMessage){
  console.debug(errorMessage); //maintain original functionality
  debugCalls[debugCalls.length]  = errorMessage;
  //the previous argument to myDebug is debugCalls[debugCalls.length]

  //you may also want to call an ajax function to report this error
  mailError(errorMessage);
}

Upvotes: 2

Related Questions