Docs API Reference

ProjectDocument.addHandlerAsync method

Asynchronously adds an event handler for a change event in a ProjectDocument object.

Hosts: Project
Available in Requirement set Selection
Added in 1.0
Office.context.document.addHandlerAsync(eventType, handler[, options][, callback]);


Name Type Description
eventType EventType The type of event to add, as an EventType constant or its corresponding text value. Required.The following table shows valid eventType arguments for a ProjectDocument object.
EnumerationText value
handler function The name of the event handler. Required.
options object Specifies any of the following optional parameters.
asyncContext array, boolean, null, number, object, string, or undefined A user-defined item of any type that is returned in the AsyncResult object without being altered.
callback object A function that is invoked when the callback returns, whose only parameter is of type AsyncResult.

Callback Value

When the callback function executes, it receives an AsyncResult object that you can access from the parameter in the callback function.

For the addHandlerAsync method, the returned AsyncResult object contains the following properties:

Name Description
asyncContext The data passed in the optional asyncContext parameter, if the parameter was used.
error Information about the error, if the status property equals failed.
status The succeeded or failed status of the asynchronous call.
value addHandlerAsync always returns undefined.


The following code example uses addHandlerAsync to add an event handler for the ViewSelectionChanged event.

When the active view changes, the handler checks the view type. It enables a button if the view is a resource view and disables the button if it isn't a resource view. Choosing the button gets the GUID of the selected resource and displays it in the add-in.

The example assumes your add-in has a reference to the jQuery library and that the following page controls are defined in the content div in the page body.

<input id="get-info" type="button" value="Get info" disabled="disabled" /><br />
<span id="message"></span>
(function () {
    "use strict";

    // The initialize function must be run each time a new page is loaded.
    Office.initialize = function (reason) {
        $(document).ready(function () {

            // After the DOM is loaded, add-in-specific code can run.
            // Add a ViewSelectionChanged event handler.

            // This example calls the handler on page load to get the active view
            // of the default page.

    // Activate the button based on the active view type of the document.
    // This is the ViewSelectionChanged event handler.
    function getActiveView() {
            function (result) {
                if (result.status === Office.AsyncResultStatus.Failed) {
                else {
                    var viewType = result.value.viewType;
                    if (viewType == 6 ||   // ResourceForm
                        viewType == 7 ||   // ResourceSheet
                        viewType == 8 ||   // ResourceGraph
                        viewType == 15) {  // ResourceUsage
                    else {
                        $('#get-info').attr('disabled', 'disabled');
                    var output = String.format(
                        'View name: {0}<br/>View type: {1}',
                        result.value.viewName, viewType);

    // Get the GUID of the currently selected resource and display it in the add-in.
    function getResourceGuid() {
            function (result) {
                if (result.status === Office.AsyncResultStatus.Failed) {
                else {
                    $('#message').html('Resource GUID: ' + result.value);

    function onError(error) {
        $('#message').html( + ' ' + error.code + ': ' + error.message);

For a complete code sample that shows how to use a TaskSelectionChanged event handler in a Project add-in, see Create your first task pane add-in for Project by using a text editor.

Support details

A capital Y in the following matrix indicates that this method is supported in the corresponding Office host application. An empty cell indicates that the Office host application doesn't support this method.

For more information about Office host application and server requirements, see Requirements for running Office Add-ins.

Office for Windows desktop Office Online (in browser)
Project Y
Available in requirement sets
Minimum permission level ReadWriteDocument
Add-in types Task pane
Library Office.js
Namespace Office

Support history

Version Changes
1.0 Introduced

See also

Other resources

TaskSelectionChanged event

removeHandlerAsync method

ProjectDocument object