The more javascript code is produced in SharePoint solutions, the more need we have to log information and possible errors to a central logging  place in SharePoint: ULS. This blog post is about logging to ULS from javascript. For a while ago I read a blog post:

• 5 suggestions to implement a better logging in SharePoint

The author @avishnyakov mentions the ability log to ULS from javascript. I want to dive deeper. [sourcecode language=“javascript”] ULS.enable = true ULSOnError(“Hello from javascript”, location.href, 0); [/sourcecode] What this function actually does, is that it calls a web service called _vti_bin/diagnostics.asmx We can follow the function in the init.debug.js [sourcecode language=“javascript”] function ULSOnError(msg, url, line) { return ULSSendExceptionImpl(msg, url, line, ULSOnError.caller); } [/sourcecode] ULSOnError invokes ULSSendExceptionImpl: [sourcecode language=“javascript”] function ULSSendExceptionImpl(msg, url, line, oCaller) { if (Boolean(ULS) && ULS.enable) { ULS.enable = false; window.onerror = ULS.OriginalOnError; ULS.WebServiceNS = “http://schemas.microsoft.com/sharepoint/diagnostics/"; try { ULS.message = msg; if (url.indexOf(’?’) != -1) url = url.substr(0, url.indexOf(’?’)); ULS.file = url.substr(url.lastIndexOf(’/’) + 1); ULS.line = line; ULS.teamName = “”; ULS.originalFile = “”; ULS.callStack = ‘\n’ + ULSGetCallstack(oCaller) + ‘’; ULS.clientInfo = ‘\n’ + ULSGetClientInfo() + ‘’; ULSSendReport(true); } catch (e) { } } if (Boolean(ULS) && Boolean(ULS.OriginalOnError)) return ULS.OriginalOnError(msg, url, String(line)); else return false; } [/sourcecode] ULSSendExceptionImpl invokes ULSSendReport: [sourcecode language=“javascript”] function ULSSendReport(async) { ULS.request = new XMLHttpRequest(); ULS.request.onreadystatechange = ULSHandleWebServiceResponse; ULS.request.open(“POST”, ULSGetWebServiceUrl(), async); ULS.request.setRequestHeader(“Content-Type”, “text/xml; charset=utf-8”); ULS.request.setRequestHeader(“SOAPAction”, ULS.WebServiceNS + “SendClientScriptErrorReport”); ULS.request.send(’’ + ‘<soap:Envelope xmlns:xsi=“http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd=“http://www.w3.org/2001/XMLSchema" xmlns:soap=“http://schemas.xmlsoap.org/soap/envelope/">' + ‘soap:Body’ + ‘’ + ‘’ + ULSEncodeXML(ULS.message) + ‘’ + ‘’ + ULSEncodeXML(ULS.file) + ‘’ + ‘’ + String(ULS.line) + ‘’ + ‘’ + ULSEncodeXML(ULS.callStack) + ‘’ + ‘’ + ULSEncodeXML(ULS.clientInfo) + ‘’ + ‘’ + ULSEncodeXML(ULS.teamName) + ‘’ + ‘’ + ULSEncodeXML(ULS.originalFile) + ‘’ + ‘’ + ‘</soap:Body>’ + ‘</soap:Envelope>’); } [/sourcecode]

Do an unsafe update in a unified manner « Sharepoint. Kunskap. Upptäckter på resan. - Sep 3, 2011

[…] Log class is my own class which I presented in my previous post. Like this:GillaBli först att gilla denna […]

Here is a simple log which has been inspired of Android Log. It logs to ULS which you can open with ULSViewer, SharePoint Log Viewer.

using System;
using Microsoft.SharePoint.Administration;

namespace Contoso.Intranet.Portal.Utilities
{
    public class Log
    {
        private static readonly string \_CATEGORYNAME = "CONTOSO";
        private static readonly SPDiagnosticsCategory \_ERROR\_CATEGORY = 
              new SPDiagnosticsCategory(\_CATEGORYNAME, TraceSeverity.Unexpected, EventSeverity.Error);
        private static readonly SPDiagnosticsCategory \_WARNING\_CATEGORY = 
              new SPDiagnosticsCategory(\_CATEGORYNAME, TraceSeverity.High, EventSeverity.Warning);
        private static readonly SPDiagnosticsCategory \_VERBOSE\_CATEGORY = 
              new SPDiagnosticsCategory(\_CATEGORYNAME, TraceSeverity.Verbose, EventSeverity.Verbose);
        private static readonly SPDiagnosticsCategory \_INFO\_CATEGORY = 
              new SPDiagnosticsCategory(\_CATEGORYNAME, TraceSeverity.Medium, EventSeverity.Information);

        private static void WriteTrace(SPDiagnosticsCategory category, string message, string trace)
        {
            SPDiagnosticsService.Local.WriteTrace(0, category, category.DefaultTraceSeverity, message, trace);
        }

        public static void Error(Exception ex)
        {
            WriteTrace(\_ERROR\_CATEGORY, ex.Message, ex.StackTrace);
        }

        public static void Warning(string message)
        {
            WriteTrace(\_WARNING\_CATEGORY, message, "");
        }

        public static void Verbose(string message)
        {
            WriteTrace(\_VERBOSE\_CATEGORY, message, "");
        }

        public static void Info(string message)
        {
            WriteTrace(\_INFO\_CATEGORY, message, "");
        }

    }
}

A possible improvement can be a custom Area. See an example of ThorstenHans on Github: CustomLogger.cs EDIT: I found an interesting article: How to log to the SharePoint ULS Logs: Clean Debugging and Error Logging broken down into steps written by Philip Stathis.