How to authenticate to SharePoint Online Site from Office scripts?

Hi rbn_neu,

To authenticate to a SharePoint Online Site from Office scripts, you can use one of the following approaches:

1. Use the Microsoft Graph API

The Microsoft Graph API is a REST API that provides access to a wide range of Microsoft 365 data, including SharePoint Online. To use the Microsoft Graph API to authenticate to a SharePoint Online site, you will need to get an OAuth 2.0 access token.

To get an OAuth 2.0 access token, you will need to register an app in Azure Active Directory (AD) and grant the app the necessary permissions to access the SharePoint Online site. Once you have registered an app and granted it the necessary permissions, you can use the following code to get an OAuth 2.0 access token:

// Get the app's client ID and client secret
const clientId = "YOUR_CLIENT_ID";
const clientSecret = "YOUR_CLIENT_SECRET";

// Get the OAuth 2.0 access token
const accessToken = await fetch("https://login.microsoftonline.com/common/oauth2/v2.0/token", {
  method: "POST",
  headers: {
    "Content-Type": "application/x-www-form-urlencoded"
  },
  body: `client_id=${clientId}&client_secret=${clientSecret}&scope=https://graph.microsoft.com/.default`
});

// Convert the access token response to JSON
const accessTokenResponse = await accessToken.json();

// Get the access token
const accessTokenValue = accessTokenResponse.access_token;​

Once you have an OAuth 2.0 access token, you can use it to authenticate to the Microsoft Graph API and access the SharePoint Online site. To access the SharePoint Online site, you will need to make a request to the following endpoint:

https://graph.microsoft.com/v1.0/sites/{siteId}

Replace {siteId} with the ID of the SharePoint Online site you want to access.

1. Use the SharePoint Online REST API

The SharePoint Online REST API is a REST API that provides access to SharePoint Online data. To use the SharePoint Online REST API to authenticate to a SharePoint Online site, you will need to get a SharePoint Online access token.

To get a SharePoint Online access token, you will need to register an app in Azure Active Directory (AD) and grant the app the necessary permissions to access the SharePoint Online site. Once you have registered an app and granted it the necessary permissions, you can use the following code to get a SharePoint Online access token:

// Get the app's client ID and client secret
const clientId = "YOUR_CLIENT_ID";
const clientSecret = "YOUR_CLIENT_SECRET";

// Get the SharePoint Online access token
const accessToken = await fetch("https://login.microsoftonline.com/common/oauth2/v2.0/token", {
  method: "POST",
  headers: {
    "Content-Type": "application/x-www-form-urlencoded"
  },
  body: `client_id=${clientId}&client_secret=${clientSecret}&scope=https://graph.microsoft.com/.default`
});

// Convert the access token response to JSON
const accessTokenResponse = await accessToken.json();

// Get the access token
const accessTokenValue = accessTokenResponse.access_token;​

Once you have a SharePoint Online access token, you can use it to authenticate to the SharePoint Online REST API and access the SharePoint Online site. To access the SharePoint Online site, you will need to make a request to the following endpoint:

https://{tenant}.sharepoint.com/_api/web/GetByServerRelativeUrl('{siteUrl}')

Replace {tenant} with the name of your SharePoint Online tenant and {siteUrl} with the URL of the SharePoint Online site you want to access.

If you need to access SharePoint Online data from other Microsoft 365 services, such as Microsoft Teams or Microsoft OneDrive, then you should use the Microsoft Graph API.

If you need to access SharePoint Online data from outside of Microsoft 365, then you should use the SharePoint Online REST API.

• Microsoft Graph API documentation: https://learn.microsoft.com/en-us/graph/
• SharePoint Online REST API documentation: https://learn.microsoft.com/en-us/sharepoint/dev/sp-add-ins/get-to-know-the-sharepoint-rest-service