Make a Microsoft graph call using javascript

Unlocking Microsoft 365 Data with JavaScript

Imagine this: your team is building a productivity app that needs to pull in user calendars, emails, or OneDrive files from Microsoft 365. You’ve heard of Microsoft Graph, the unified API endpoint for accessing Microsoft 365 data, but you’re not sure where to start. The documentation feels overwhelming, and you just want to see a working example in JavaScript. Sound familiar?

Microsoft Graph is a goldmine for developers. It allows you to interact with Microsoft 365 services like Outlook, Teams, OneDrive, and more—all through a single API. But getting started can be tricky, especially when it comes to authentication and managing API calls securely. In this guide, I’ll walk you through how to set up and make your first Microsoft Graph API call using JavaScript. Along the way, I’ll share some hard-earned lessons, gotchas, and tips to ensure your implementation is both functional and secure.

Before We Dive In: Security Implications

Before writing a single line of code, let’s talk security. Microsoft Graph requires OAuth 2.0 for authentication, which means you’ll need to handle access tokens. These tokens grant access to sensitive user data, so mishandling them can lead to serious security vulnerabilities.

Additionally, always request the minimum set of permissions (scopes) your app needs. Over-permissioning is not only a security risk but also a violation of Microsoft’s best practices.

Step 1: Setting Up the Microsoft Graph JavaScript Client Library

The easiest way to interact with Microsoft Graph in JavaScript is by using the official @microsoft/microsoft-graph-client library. This library simplifies the process of making HTTP requests and handling responses.

First, install the library via npm:

npm install @microsoft/microsoft-graph-client

Once installed, you’ll also need an authentication library to handle OAuth 2.0. For this example, we’ll use msal-node, Microsoft’s official library for authentication in Node.js: