onerror + ErrorEvent, onerror preventing default

Result: ErrorEvent still fires anyway

by James Greene

JavaScript

window.onerror = function() {
    document.body.innerHTML += "<div>onerror</div>";
    
    // Will this prevent `ErrorEvent` from firing?
    return true;
}

if (typeof window.ErrorEvent !== "undefined") {
    window.addEventListener("error", function() {
        document.body.innerHTML += "<div>ErrorEvent</div>";
    });
}
else {
    document.body.innerHTML += "<div>ErrorEvent not available in this browser</div>";
}

throw new Error("WAT");