检测 console.warn 消息

Question

I have a need to find out when a warning (not error) message is sent to the browser's console.log . From research, I know that I can detect error messages with JavaScript code similar to this:

window.onerror = function(errorMsg, url, lineNumber){
    // any action you want goes here
    // errorMsg is the error message itself.
    // url should be the file presenting the error, though i have
    //    found that it only presents to me the address of the site.
    // lineNumber is the line number the error occoured on.
    // here is an example of what you could do with it:
    alert("Error in " + url + " at " + lineNumber + ":\n" + errorMsg);
}

But that only shows error messages. It will not show any warning messages.

Is there a similar way to detect a specific warning message in the console.log? Or, alternately, is there some JS code that will allow me to search the console.log for a specific string?

Note that I can see the warning message in the browser's debugging (console logging) window. But I want to 'intercept' the warning message and perform some action if that warning is found.

Added

The intent is to find out when a specific warning message occurs; the message being similar to "Loading failed for the <script> with source "https://www.example.com/js/somescript.js" .

But the question of how to intercept a warning message (not error; the code I included does that) that is output by the browser (not my code).

Added

So, here's what I need. Assume this code

console.warn("Here is a warning!");

What code would you write to see if that message was written to the console as a warning?

Answer 1

How about overriding the console.log() ?

 let tmpConsoleLog = console.log; console.log = function(msg){ // Intercept code goes here using msg variable alert(msg); // then perform the normal logging tmpConsoleLog(msg); } console.log("Something");

Answer 2

The warnings you are talking about are generated by the browser, not console.warn . This is why you cannot override it. Most likely, you need to manually add listeners for each event you need. For example, if you want to handle a script loading error use the onerror event:

 <script src="https://www.example.com/js/somescript1.js" onerror="console.log('Cannot load script from ' + this.src)"></script> <script src="https://www.example.com/js/somescript2.js" onerror="console.log('Cannot load script from ' + this.src)"></script>

Answer 3

It's very late, but here's an answer that actually directly answers your question.

 var originalConsoleWarn = console.warn; console.warn = function(message) { doSomethingWithWarn(message); originalConsoleWarn(message); }; function doSomethingWithWarn(message){ console.log("DOING SOMETHING WITH: " + message); } console.warn("hi");