App Extensions - EXPRESSO Docs

App Extensions let you customize specific parts of the mobile application with JavaScript. Each App Extension has its own purpose. You write the logic for the extension, and Expresso runs it at the right moment.

How App Extensions Work

Each App Extension runs through a specific named function. Your project must export that function. Expresso looks for the exported function with the expected name for each extension, extracts it, and runs it when that extension is needed. For example, if an extension expects a function named runProductExtension, your project must export runProductExtension:

export const runProductExtension = (products: ProductListingBaseDataEditor[]) => {
  return;
};

You can write the function in another file, but it still needs to be exported by your project entry file:

import { runProductExtension } from "./src/extension";

export { runProductExtension };

The function name matters. If the expected function is not exported, Expresso cannot run that App Extension.

Available App Extensions

The app currently supports these App Extensions.

Product Listing Formatter Extension

Use this extension to customize how products appear in product lists. For example, you can change product display data, add labels, adjust tags, or hide products from a listing when your rules say they should not appear.

Cart Operations App Extension

Use this extension to customize cart behavior. For example, you can react to cart operations, apply custom rules, or control how cart-related actions should behave.

Product Detail Handler App Extension

Use this extension to customize behavior on the product detail page. For example, you can format product information, react when a product is selected, handle add-to-cart events, or customize what happens when the user clicks product-related actions.

Next Steps

Each App Extension has its own contract, inputs, and outputs. Use the specific App Extension pages to learn how to implement each one.

​How App Extensions Work

​Available App Extensions

​Product Listing Formatter Extension

​Cart Operations App Extension

​Product Detail Handler App Extension

​Next Steps