FormData

npm install formdata-polyfill

A FormData polyfill

This polyfill conditionally replaces the native implementation rather then fixing the missing functions, since otherwise there is no way to get or delete existing values in the FormData object. Therefore this also patches XMLHttpRequest.prototype.send and fetch to send the FormData as a blob, and navigator.sendBeacon to send native FormData.

I was unable to patch the Response/Request constructor so if you are constructing them with FormData you need to call fd._blob() manually.

new Request(url, {
  method: 'post',
  body: fd._blob ? fd._blob() : fd
})

Dependencies

If you need to support IE <= 9 then I recommend you to include eligrey's blob.js

var FormData = require('formdata-polyfill')
var fd = new FormData(form)
xhr.send(fd._blob())

require('formdata-polyfill')
var fd = new FormData(form)
xhr.send(fd)

Native Browser compatibility (as of 2020-01-13)

Based on this you can decide for yourself if you need this polyfill.

This polyfill normalizes support for the FormData API:

• append with filename
• delete(), get(), getAll(), has(), set()
• entries(), keys(), values(), and support for for...of
• Available in web workers (just include the polyfill)