Save Blob as file in JavaScript

data-url.js

// In this file we use a data URL to represent a Blob. This basically base64
// encodes the Blob and puts that string in a URL. This has better compatibility
// with old browsers, but is limited to ~2MB.

const blob = getBlobFromSomewhere()

const reader = new FileReader()
reader.onload = function (event) {
  const a = document.createElement('a')
  a.href = event.target.result
  a.download = 'example.xlsx'
  a.click()
}
reader.readAsDataURL(blob)

object-url.js

// In this file we use an object URL to represent a Blob. Object URLs refer
// to a Blob or File in memory and are bound to the document they are
// created in. For details see:
// https://developer.mozilla.org/en-US/docs/Web/API/URL/createObjectURL
// There doesn't seem to be a hard limit on the file size. The average limit
// seems to be ~600MiB

const blob = getBlobFromSomewhere()
const objectUrl = window.URL.createObjectURL(blob);

const a = document.createElement('a')
a.href = objectUrl
a.download = 'example.xlsx'
a.click()

// It is important to revoke the object URL after it's no longer used for
// memory management.
URL.revokeObjectURL(objectUrl)