Read a file with XLSX.readFile

Question

In Typescript, I've got the error "Cannot read property 'replace' of undefined" executing:

const xlsx = XLSX.readFile(fileName);

filename is a path to an existing file; I've read that "readFile is only available in server environments. Browsers have no API for reading arbitrary files given a path, so another strategy must be used." How can I do?

Edit: the file I'm trying to read is an xlsx; it's zipped: does the library have a bug? I'm running xlsx@0.15.1

Split your questions please. You asking one thing, then changing the subject. — mayakwd, Sep 10 '19 at 19:48

score 3 · Answer 1 · answered Sep 10 '19 at 13:53

NodeJS API allows you to work with file system API.
Browser API allows you to fetch any kind of data from server.

So basically you need to place your file on some server (local or remote), then fetch it and read it with XLSX.read(data, options)

fetch('http://localhost:8080/public/filename.ext')
   .then(response => response.arrayBuffer())
   .then(buffer => {
         const xlsx = XLSX.read(new Uint8Array(data, {type: 'array'}));
         // process data here
         ...
    })
    .catch(err => console.error(err));

The other way, if you don't want to host your file on the server, you can try FileReader API, which is a bit more complicated.

You can read about FileReader and File in this article: "Reading files in JavaScript using the File APIs"

I suspect is a bug of XLSX. readFile with compressed files (i.e. xlsx) — user1, Sep 11 '19 at 16:30

score 3 · Answer 2 · answered Nov 17 '20 at 00:47

reading a file in xlsx is easy and flexible, you can store data in db or in json file, so that later you can render the data

 <input
        type="file"
        onChange={e => {
          const file = e.target.files[0]
          readExcel(file)
        }}
/>

now read the file when you upload it

const readExcel = async (file: any) => {
    const fileReader = await new FileReader()
    fileReader.readAsArrayBuffer(file)

    fileReader.onload = (e: any) => {
      const bufferArray = e?.target.result
      const wb = XLSX.read(bufferArray, { type: "buffer" })
      const wsname = wb.SheetNames[0]
      const ws = wb.Sheets[wsname]

      const data = XLSX.utils.sheet_to_json(ws)
      const fileName = file.name.split(".")[0]

      console.log(data)
    }

github repo

Is async necessary? Thanks so much for this answer, Ive been searching for it. — Muhammad Mubashirullah Durrani, Aug 31 '23 at 11:25

Read a file with XLSX.readFile

2 Answers2

Linked