Clientside error logging using Elmah

Question

I'm using ELMAH to log my .net errors. It's working great, but I want to extend the error logging to include client side errors, i.e arbitrary JavaScript errors. I can capture the errors using window.onerror event and then call a .net handler (.ashx) to log the error in elmah, but this is just my little hack to solve the problem. Is there a better way to log client side error to elmah?

Answer 1

Here's a more complete solution (I think I grabbed it from the ELMAH site... can't remember)

ErrorLogging.js:

    window.onerror = function (msg, url, line) {
        logError(msg, arguments.callee.trace());
    }
    function logError(ex, stack) {
        if (ex == null) return;
        if (logErrorUrl == null) {
            alert('logErrorUrl must be defined.');
            return;
        }

        var url = ex.fileName != null ? ex.fileName : document.location;
        if (stack == null && ex.stack != null) stack = ex.stack;

        // format output
        var out = ex.message != null ? ex.name + ": " + ex.message : ex;
        out += ": at document path '" + url + "'.";
        if (stack != null) out += "\n  at " + stack.join("\n  at ");

        // send error message
        jQuery.ajax({
            type: 'POST',
            url: logErrorUrl,
            data: { message: out }
        });
    }

    Function.prototype.trace = function()
    {
        var trace = [];
        var current = this;
        while(current)
        {
            trace.push(current.signature());
            current = current.caller;
        }
        return trace;
    }

    Function.prototype.signature = function()
    {
        var signature = {
            name: this.getName(),
            params: [],
            toString: function()
            {
                var params = this.params.length > 0 ?
                    "'" + this.params.join("', '") + "'" : "";
                return this.name + "(" + params + ")"
            }
        };
        if (this.arguments)
        {
            for(var x=0; x<this.arguments.length; x++)
                signature.params.push(this.arguments[x]);
        }
        return signature;
    }

    Function.prototype.getName = function()
    {
        if (this.name)
            return this.name;
        var definition = this.toString().split("\n")[0];
        var exp = /^function ([^\s(]+).+/;
        if (exp.test(definition))
            return definition.split("\n")[0].replace(exp, "$1") || "anonymous";
        return "anonymous";
    }

Layout/Master Page:

<script src="@Url.Content( "~/Scripts/ErrorLogging.js" )" type="text/javascript"></script>

<script type="text/javascript">
    //This needs to be here to be on everypage
    var logErrorUrl = '@Url.Action( "LogJavaScriptError", "Home" )';
</script>

HomeController.cs:

    [HttpPost]
    public void LogJavaScriptError( string message ) {
        ErrorSignal.FromCurrentContext().Raise( new JavaScriptErrorException( message ) );
    }

JavaScriptErrorException.cs:

[Serializable]
public class JavaScriptErrorException: Exception{
    public JavaScriptErrorException( string message ) : base ( message ){}
}

Answer 2

Take a look at hoptoadapp.com and how they do javascript reporting.

It's the exact same thing, but a different backend :-)