The JavaScript API for Office enables you to create web applications that interact with the object models in Office host applications. Your application will reference the office.js library, which is a script loader. The office.js library loads the object models applicable to the Office application running the add-in.

The NPM package for Office.js is a copy of what gets published to the official "evergreen" Office.js CDN, at https://appsforoffice.microsoft.com/lib/1/hosted/office.js.

The Office.js CDN contains all currently available Office.js APIs at any moment in time.

Each Office.js NPM package contains only Office.js APIs available on the Office.js CDN when the NPM package version was created.

The NPM package for Office.js is intended as a way to obtain an offline copy (non-CDN) of the Office.js files, which can then be statically serve from your own site instead of using the CDN.

This NPM package is provided for the following scenarios.

1. Development of an add-in behind a firewall, when accessing the Office.js CDN isn't possible.
2. Offline access to the Office.js APIs to facilitate offline debugging.

Important: Office Add-ins published to AppSource must use the CDN reference. Offline Office.js references are only appropriate for internal development and debugging scenarios.

Best practices for using the Office.js NPM package include:

• Refreshing the NPM package periodically to access new APIs and bug fixes.

• Using the NPM package according to the instructions. Do not import the NPM package as commonly done with other NPM packages.

• Do not use the NPM package in an add-in intended for publication to AppSource. Add-ins that are published to AppSource must use the Office.js CDN.

• Using TypeScript definitions for Office.js.

The Office.js CDN is the official supported source for Office Add-ins.

For the NPM package sourced through this repository, only the latest version of the package is supported. No support and no patches will be provided for previous versions of the package. The frequency of the updates to this repository and related NPM package to match the CDN version is not guaranteed.

Outlook add-ins don't support hosting Office.js offline due to network access requirements for dependencies like the Microsoft Ajax library.

To install "office-js" locally via the NPM package, run the following command.

npm install @microsoft/office-js --save

Our policy requires that developers always reference the latest version of Office.js library. This is to ensure that essential product updates are served quickly to the Office Add-ins by always referencing the latest release of the library for a given version, such as Generally Available (GA) version. Given that the latest Office.js release is backward-compatible with prior releases, it's safe to update to the most recent release of the library when one is available. Hence, only the latest version of Office.js NPM package is made available for installation.

Installing the NPM package locally creates a set of static Office.js files in the node_modules\@microsoft\office-js\dist folder of the directory where you ran the npm install command. To use the NPM package, do the following:

1. Either manually or as part of a build script (e.g., CopyWebpackPlugin if you're using Webpack) have the files served from a destination of your choosing (e.g., from the /assets/office-js/ directory of your web server).

2. Reference that location in a <script> tag within the HTML file in your add-in project.

For example, if you add the contents of the dist folder to the assets/office-js directory of your project, then you'd add the following <script> tag to your HTML file:

<script src="/assets/office-js/office.js"></script>

TypeScript definitions for Office.js are available.

• latest RELEASE version of Office.js:
  • DefinitelyTyped: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/office-js/index.d.ts
  • @types: @types/office-js

  npm install @types/office-js --save-dev

• latest BETA version of Office.js:
  • DefinitelyTyped: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/office-js-preview/index.d.ts
  • @types: @types/office-js-preview.

  npm install @types/office-js-preview --save-dev

• any version:
  • Inside of the NPM package, under dist/office.d.ts
  • In this repo: dist/office.d.ts

If you're using the Office.js NPM package for the firewall scenario and want a d.ts file that precisely matches the JS contents, use the d.ts file that's located within the /dist/office.d.ts folder of the NPM package. Achieve this by using a triple-slash reference.

• TIP: If you create a references.ts file at the root of the project, simply point the reference to office.d.ts there.

If you don't need the firewall scenario, don't use the Office.js NPM package. Obtain the TypeScript definitions by using @types/office-js and reference the Office.js CDN at https://appsforoffice.microsoft.com/lib/1/hosted/office.js.

Visual Studio 2017 can use these same TypeScript definitions, even for regular JavaScript. For JavaScript IntelliSense in earlier versions of Visual Studio, an office-vsdoc.js is available alongside the office.js file. As long as you have a Scripts/_references.js file in your VS project, and as long as you substitute the existing triple-slash reference (/// <reference path="https://.../office.js" />) with the new location (the -vsdoc part gets substituted automatically, so use it just as you would in a <script src=""> reference), you should have the corresponding JavaScript IntelliSense.

Office.js versioning is described in detail in https://learn.microsoft.com/office/dev/add-ins/develop/referencing-the-javascript-api-for-office-library-from-its-cdn. Importantly, there's a difference between what's in the JS files versus what are the capabilities of a particular computer (i.e., older or slower-to-update versions of Office).

The NPM package and the repo branches assume the following structure.

This project has adopted the Microsoft Open Source Code of Conduct. For more information, see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.

For more information on Office Add-ins and the Office JavaScript APIs, see:

• Office Add-ins platform overview
• JavaScript API for Office reference

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