Access window.console after overwrite

Question

Is it possible to somehow access to console.log after it gets overwritten?

window.console = { log: function (msg) { alert(msg); }, /* etc... */ };


        

Answer 1

You can back up the console before overwriting it.

var oldConsole = window.console;
window.console = { log:function(msg){alert(msg)} //...};

Then you can use the oldConsole variable.

oldConsole.log('test');

If you can't back it up, you can create an iFrame, and then steal the console from there (this may not work in all browsers):

var i = document.createElement('iframe');
i.style.display = 'none';
document.body.appendChild(i);
window.console = i.contentWindow.console;

Demo: http://jsfiddle.net/jcG7E/2

Answer 2

var customLog = {
    oriLog: '',
    Log: function(){
        // create string to display
        var displaystring = '';
        for (var i = 0, len = arguments.length; i < len; i++) {
            displaystring += arguments[i];
            if (i + 1 != len) 
                displaystring += ', ';
        }
        alert(displaystring);
        customLog.oriLog(arguments);
    }
}
window.onload = function(){
    if (console != null) {
        customLog.oriLog = console.log;
        console.log = customLog.Log;
    }

}

Answer 3

It's not possible. Except if whoever has overwritten it has included some code to undo it.

Answer 4

Edit (2017-04-08): This advise is outdated, in Firefox 52 and Chrome 57 console is no longer defined on the window prototype and deleting it will really delete it.

---

At least with the console object defined by Firefox and Chrome, you can simply delete the overwritten property to restore the original one:

window.console = {};
delete window.console;
window.console.log("This works!");

This works as if the console property were defined on the prototype of the window object - except that it isn't, the browsers are doing some magic here.