Debug.msTraceAsyncOperationStarting Function

Initiates a trace for an asynchronous operation.



Required. A string that identifies the asynchronous operation. If operationName is null or undefined, an empty string is used for the operation name.

An integer representing the operation ID.

Call this method before the asynchronous operation starts.

Note Note

Some debugging tools, such as F12 developer tools, do not display the information sent to the debugger. Visual Studio supports this function and shows relevant information in the call stack and the Tasks window.

The following code provides an example of instrumenting an asynchronous call for a Windows Store app.

function asyncWrapperFunction() {
    var opID = Debug.msTraceAsyncOperationStarting('async trace');
    doSomethingAsync().then(function (result) {
        Debug.msTraceAsyncOperationCompleted(opID, Debug.MS_ASYNC_OP_STATUS_SUCCESS);
        // Process result of async operation.
    }, function (error) {
        Debug.msTraceAsyncOperationCompleted(opID, Debug.MS_ASYNC_OP_STATUS_ERROR);


function doSomethingAsync() {


Supported in the Internet Explorer 11 standards document mode. Also supported in Store apps (Windows 8.1 and Windows Phone 8.1). See Version Information. Not supported in the following document modes: Quirks, Internet Explorer 6 standards, Internet Explorer 7 standards, Internet Explorer 8 standards, Internet Explorer 9 standards, Internet Explorer 10 standards. Not supported in Windows 8.

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