Code - TypeScript

Office.initialize = function (reason) { 
  $(document).ready(function () { 

    // Set up ItemChanged event 
    Office.context.mailbox.addHandlerAsync(Office.EventType.ItemChanged, itemChanged); 

    UpdateTaskPaneUI(Office.context.mailbox.item); 
  }); 
}; 

Delegate Access

function performOperation() { 
  Office.context.mailbox.getCallbackTokenAsync({ 
      isRest: true 
    }, 
    function (asyncResult) { 
      if (asyncResult.status === Office.AsyncResultStatus.Succeeded && asyncResult.value !== "") { 
        Office.context.mailbox.item.getSharedPropertiesAsync({ 
            // Pass auth token along. 
            asyncContext: asyncResult.value 
          }, 
          function (asyncResult1) { 
            let sharedProperties = asyncResult1.value; 
            let delegatePermissions = sharedProperties.delegatePermissions; 

            // Determine if user can do the expected operation. 
            // E.g., do they have Write permission? 
            if ((delegatePermissions & Office.MailboxEnums.DelegatePermissions.Write) != 0) { 
              // Construct REST URL for your operation. 
              // Update <version> placeholder with actual Outlook REST API version e.g. "v2.0". 
              // Update <operation> placeholder with actual operation. 
              let rest_url = sharedProperties.targetRestUrl + "/<version>/users/" + sharedProperties.targetMailbox + "/<operation>"; 
  
              $.ajax({ 
                  url: rest_url, 
                  dataType: 'json',  
                  headers: 
                  { 
                    "Authorization": "Bearer " + asyncResult1.asyncContext 
                  } 
                } 
              ).done( 
                function (response) { 
                  console.log("success"); 
                } 
              ).fail( 
                function (error) { 
                  console.log("error message"); 
                } 
              ); 
            } 
          } 
        ); 
      } 
    } 
  ); 
} 

Get Access Token

link - learn.microsoft.com/previous-versions/office/office-365-api/api/version-2.0/mail-rest-operations#get-messages.

Office.context.mailbox.getCallbackTokenAsync({isRest: true}, function(result){ 
  if (result.status === "succeeded") { 
    var accessToken = result.value; 

    // Use the access token. 
    getCurrentItem(accessToken); 
  } else { 
    // Handle the error. 
  } 
}); 

function getItemRestId() { 
  if (Office.context.mailbox.diagnostics.hostName === 'OutlookIOS') {  
    // itemId is already REST-formatted. 
    return Office.context.mailbox.item.itemId; 
  } else { 
    // Convert to an item ID for API v2.0. 
    return Office.context.mailbox.convertToRestId( 
      Office.context.mailbox.item.itemId, 
      Office.MailboxEnums.RestVersion.v2_0 
    ); 
  } 
} 

function getCurrentItem(accessToken) { 
  // Get the item's REST ID.  
  var itemId = getItemRestId(); 

  // Construct the REST URL to the current item. 
  // Details for formatting the URL can be found at 
  var getMessageUrl = Office.context.mailbox.restUrl + 
    '/v2.0/me/messages/' + itemId;

  $.ajax({ 
    url: getMessageUrl, 
    dataType: 'json',  
    headers: { 'Authorization': 'Bearer ' + accessToken }  
  }).done(function(item){ 
    // Message is passed in `item`. 
    var subject = item.Subject; 
    ... 
  }).fail(function(error){ 
    // Handle error. 
  }); 
} 

Master Categories

var masterCategoriesToAdd = [ 
    { 
        "displayName": "Urgent!", 
        "color": Office.MailboxEnums.CategoryColor.Preset0 
    } 
]; 

Office.context.mailbox.masterCategories.addAsync(masterCategoriesToAdd, function (asyncResult) { 
    if (asyncResult.status === Office.AsyncResultStatus.Succeeded) { 
        console.log("Successfully added categories to master list"); 
    } else { 
        console.log("masterCategories.addAsync call failed with error: " + asyncResult.error.message); 
    } 
}); 

Office.context.mailbox.masterCategories.getAsync(function (asyncResult) { 
    if (asyncResult.status === Office.AsyncResultStatus.Failed) { 
        console.log("Action failed with error: " + asyncResult.error.message); 
    } else { 
        var masterCategories = asyncResult.value; 
        console.log("Master categories:"); 
        masterCategories.forEach(function (item) { 
            console.log("-- " + JSON.stringify(item)); 
        }); 
    } 
}); 

var masterCategoriesToRemove = ["Urgent!"]; 

Office.context.mailbox.masterCategories.removeAsync(masterCategoriesToRemove, function (asyncResult) { 
    if (asyncResult.status === Office.AsyncResultStatus.Succeeded) { 
        console.log("Successfully removed categories from master list"); 
    } else { 
        console.log("masterCategories.removeAsync call failed with error: " + asyncResult.error.message); 
    } 
}); 

Office.context.mailbox.item.categories.getAsync(function (asyncResult) { 
    if (asyncResult.status === Office.AsyncResultStatus.Failed) { 
        console.log("Action failed with error: " + asyncResult.error.message); 
    } else { 
        var categories = asyncResult.value; 
        console.log("Categories:"); 
        categories.forEach(function (item) { 
            console.log("-- " + JSON.stringify(item)); 
        }); 
    } 
}); 

Setting Recurrence

var seriesTimeObject = new Office.SeriesTime(); seriesTimeObject.setStartDate(2019,10,2); 
seriesTimeObject.setEndDate(2019,11,2); 
seriesTimeObject.setStartTime(10,30); 
seriesTimeObject.setDuration(30); 

var pattern = { 
    "seriesTime": seriesTimeObject, 
    "recurrenceType": "weekly", 
    "recurrenceProperties": {"interval": 1, "days": ["tue", "thu"]}, 
    "recurrenceTimeZone": {"name": "Pacific Standard Time"}}; 

Office.context.mailbox.item.recurrence.setAsync(pattern, callback); 

function callback(asyncResult) 
{ 
    console.log(JSON.stringify(asyncResult)); 
}