Prefer const/let over var

[mirror_novnc.git] / app / error-handler.js

// NB: this should *not* be included as a module until we have
// native support in the browsers, so that our error handler
// can catch script-loading errors.

(function(){
    "use strict";

    // Fallback for all uncought errors
    function handleError (event, err) {
        try {
            const msg = document.getElementById('noVNC_fallback_errormsg');

            // Only show the initial error
            if (msg.hasChildNodes()) {
                return false;
            }

            let div = document.createElement("div");
            div.classList.add('noVNC_message');
            div.appendChild(document.createTextNode(event.message));
            msg.appendChild(div);

            if (event.filename) {
                div = document.createElement("div");
                div.className = 'noVNC_location';
                let text = event.filename;
                if (event.lineno !== undefined) {
                    text += ":" + event.lineno;
                    if (event.colno !== undefined) {
                        text += ":" + event.colno;
                    }
                }
                div.appendChild(document.createTextNode(text));
                msg.appendChild(div);
            }

            if (err && err.stack) {
                div = document.createElement("div");
                div.className = 'noVNC_stack';
                div.appendChild(document.createTextNode(err.stack));
                msg.appendChild(div);
            }

            document.getElementById('noVNC_fallback_error')
                .classList.add("noVNC_open");
        } catch (exc) {
            document.write("noVNC encountered an error.");
        }
        // Don't return true since this would prevent the error
        // from being printed to the browser console.
        return false;
    }
    window.addEventListener('error', function (evt) { handleError(evt, evt.error); });
    window.addEventListener('unhandledrejection', function (evt) { handleError(evt.reason, evt.reason); });
})();