JS Error Catching

ErrorHandler.js

(function ErrorHandler(errorElement) {
    var self = this;
    self.errorcount = 0;
    self.onerror = onerror;
    self.originalOnerror = window.onerror;
    self.revertErrorHandler = revertErrorHandler;
    window.onerror = self.onerror;

    window.onload = onload;

    function onload() {
        revertErrorHandler();
        if (self.errorcount > 0) {
            document.getElementById(errorElement).style.display = 'block'
        }
    }

    function onerror(msg, url, line, col, error) {
        self.errorcount++;
        return false;
    }
    function revertErrorHandler() {
        window.onerror = self.originalOnerror;
    }
})('unsupported-browser');