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WebView2 / CoreWebView2 - Detecting if a javascript error happens

I have written a web-crawler to test a pre-release website for errors and issues (i.e. missing content type, timeouts, exceptions, redirects).
This morning a colleague asked me to include a check if there was any javascript error on the page...
A pure javascript solution is unlikely -- i.e. detect all JS errors, using JS
What I appear to want to be able to do is capture the javascript console text, ideally via CoreWebView2

If the page logs each exception into an array,
Errors=[]
window.onerror = function (msg, url, line) {
Errors.push("Caught[via window.onerror]: '" + msg + "' from " + url + ":" + line);
return true;
};
Then you can just query the Errors and see both the count and the nature of the errors.
You can also push errors from try catch

Script Stopped working after PHP5 > PHP7.2?

I came across this problem recently that I have no idea what caused it. This script makes my wp custom taxonomy list act like a tree accordion menu, but this script broke - I had to find out through a member of the site.
I am too far ahead into updating the site to be able to turn back time. However 1 major thing I did was upgrade from PHP5 to PHP7.2 on the server so I am not sure if that broke it. Here is the script in question:
<script>
function addExpandCollapse(id, expandSym, collapseSym, accordion) {jQuery('#' + id + ' .expand').live('click', function() {
if (accordion==1) {
var theDiv = jQuery(this).parent().parent().find('span.collapse').parent().find('div');
jQuery(theDiv).hide('normal');
jQuery(this).parent().parent().find('span.collapse').removeClass('collapse').addClass('expand');
createCookie(theDiv.attr('id'), 0, 7);
}
jQuery('#' + id + ' .expand .sym').html(expandSym);
expandCat(this, expandSym, collapseSym);
return false;
});
jQuery('#' + id + ' .collapse').live('click', function() {
collapseCat(this, expandSym, collapseSym);
return false;
});
}
</script>
The error on Safari displays
TypeError: undefined is not a function (near '...jQuery('#' + id + ' .expand').live...')
But this error never occurred back then so I am not sure if the code is not PHP7.2 compliant. I am really new to PHP, and fairly a student to Javascript. Any advice?

Try change .live('click') to .on('click')

Detect a console.warn message

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?

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>

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");

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");

Generic Ajax Error Handling - interceptor in Angular JS

I want to implement the global error handling for Ajax calls in my angular Js Application . I think $httpprovider works for $http requests only. Kindly guide me in achieving this. How can i write the interceptor for capturing the failure of Ajax calls. My main goal is to capture the failure of Ajax call into google Analytics.

Write ajax call inside javascripts try-catch
http://www.w3schools.com/js/js_errors.asp

You can try to listen to window.onerror event but it will catch all js errors, so you need to filter them.
window.onerror = function(msg, url, line, col, error) {
// Note that col & error are new to the HTML 5 spec and may not be
// supported in every browser. It worked for me in Chrome.
var extra = !col ? '' : '\ncolumn: ' + col;
extra += !error ? '' : '\nerror: ' + error;
// You can view the information in an alert to see things working like this:
alert("Error: " + msg + "\nurl: " + url + "\nline: " + line + extra);
// TODO: Report this error via ajax so you can keep track
// of what pages have JS issues
var suppressErrorAlert = true;
// If you return true, then error alerts (like in older versions of
// Internet Explorer) will be suppressed.
return suppressErrorAlert;
};
You can read more about it in this question.

Phantomjs check if javascript exists and is working

I am quite new to Phantomjs and am starting to getting to know how to use it. However all of the semi advanced tutorials does not cover the thing i want to use Phantomjs for.
Now my question is how would i check if a Javascript is active on the site and if it is working correcly (i.e not throwing erros in the console).
I hope someone is able to point me in the right direction or know how to do this.

you can interact with the open page using the webpage.evaluate method:
var page = require('webpage').create();
page.open('http://m.bing.com', function(status) {
var title = page.evaluate(function(s) {
//what you do here is done in the context of the page
//this console.log will appear in the virtual page console
console.log("test")
//here they are just returning the page title (tag passed as argument)
return document.querySelector(s).innerText;
//you are not required to return anything
}, 'title');
console.log(title);
phantom.exit(); //closes phantom, free memory!
});
in order to see the virtual page console, you have to add a onConsoleMessage callback:
page.onConsoleMessage = function(msg, lineNum, sourceId) {
console.log('CONSOLE: ' + msg + ' (from line #' + lineNum + ' in "' + sourceId + '")');
};
EDIT: by default javascript is executed.