JavaScript
Wereldwijde foutafhandeling in browsers

Syntaxis

• window.onerror = function (eventOrMessage, url, lineNumber, colNumber, error) {...}

parameters

Opmerkingen

Window.onerror afhandelen om alle fouten aan de server te melden

In het volgende voorbeeld wordt naar de gebeurtenis window.onerror en wordt een afbeeldingbakentechniek gebruikt om de informatie via de GET-parameters van een URL te verzenden.

var hasLoggedOnce = false;

// Some browsers (at least Firefox) don't report line and column numbers
// when event is handled through window.addEventListener('error', fn). That's why
// a more reliable approach is to set an event listener via direct assignment.
window.onerror = function (eventOrMessage, url, lineNumber, colNumber, error) {
    if (hasLoggedOnce || !eventOrMessage) {
        // It does not make sense to report an error if:
        // 1. another one has already been reported -- the page has an invalid state and may produce way too many errors.
        // 2. the provided information does not make sense (!eventOrMessage -- the browser didn't supply information for some reason.)
        return;
    }
    hasLoggedOnce = true;
    if (typeof eventOrMessage !== 'string') {
        error = eventOrMessage.error;
        url = eventOrMessage.filename || eventOrMessage.fileName;
        lineNumber = eventOrMessage.lineno || eventOrMessage.lineNumber;
        colNumber = eventOrMessage.colno || eventOrMessage.columnNumber;
        eventOrMessage = eventOrMessage.message || eventOrMessage.name || error.message || error.name;
    }
    if (error && error.stack) {
        eventOrMessage = [eventOrMessage, '; Stack: ', error.stack, '.'].join('');
    }
    var jsFile = (/[^/]+\.js/i.exec(url || '') || [])[0] || 'inlineScriptOrDynamicEvalCode',
        stack = [eventOrMessage, ' Occurred in ', jsFile, ':', lineNumber || '?', ':', colNumber || '?'].join('');

    // shortening the message a bit so that it is more likely to fit into browser's URL length limit (which is 2,083 in some browsers)
    stack = stack.replace(/https?\:\/\/[^/]+/gi, '');
    // calling the server-side handler which should probably register the error in a database or a log file
    new Image().src = '/exampleErrorReporting?stack=' + encodeURIComponent(stack);
    
    // window.DEBUG_ENVIRONMENT a configurable property that may be set to true somewhere else for debugging and testing purposes.
    if (window.DEBUG_ENVIRONMENT) {
        alert('Client-side script failed: ' + stack);
    }
}