Read console.log() output form javascript

Question

I am writing an overlay UI for one application using Greasemonkey, injecting JS to a page.

Now I have issue to hook on some ajax calls that runs on the webpage. However, the page is generating console logs, informing that content is fully loaded. My question is:

In plain javascript, is there a possibility of reading console output generated by completely different script?

function blackBox(){
   //this is generating come console output.
   //this runs on code layer I have no access to.
}

function readConsole(){
   //read console record by record
   if(console.msg == "something I want"){
      doSomething();
   }

}

Thanks in advance :)

Answer 1

As others have stated, you can override the console.log() function with your own, and implement your own implementation:

var oldLog = unsafeWindow.console.log;
var messages = [];

unsafeWindow.console.log = function(msg) {
    messages.push(msg);
    oldLog.apply(null, arguments);
}

// Access the entire console.log history in messages