sheetjs/demos/xhr

XMLHttpRequest and Friends

XMLHttpRequest and fetch browser APIs enable binary data transfer between web browser clients and web servers. Since this library works in web browsers, server conversion work can be offloaded to the client! This demo shows a few common scenarios involving browser APIs and popular wrapper libraries.

Sample Server

The server.js nodejs server serves static files on GET request. On a POST request to /upload, the server processes the body and looks for the file and data fields. It will write the Base64-decoded data from data to the file name specified in file.

To start the demo, run npm start and navigate to http://localhost:7262/

XMLHttpRequest (xhr.html)

For downloading data, the arraybuffer response type generates an ArrayBuffer that can be viewed as an Uint8Array and fed to XLSX.read using array type.

For uploading data, this demo populates a FormData object with string data generated with the base64 output type.

axios (axios.html) and superagent (superagent.html)

The codes are structurally similar to the XMLHttpRequest example. axios uses a Promise-based API while superagent opts for a more traditional chain.

fetch (fetch.html)

For downloading data, response.blob() resolves to a Blob object that can be converted to ArrayBuffer using a FileReader.