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FormData.entries ponyfill

This ponyfill implements the FormData serialization algorithm. It aims to be compatible with calling the native new FormData(form).entries(). jQuery's serializeArray is another implementation example.


import formDataEntries from 'form-data-entries'

for (const [name, value] of formDataEntries(myForm)) {

Why ponyfill?

This package implements FormData.entries as a module ponyfill rather than a polyfill. FormData.entries was a later addition to the FormData specification. Therefore browsers may support FormData but not the entries method. It would be dangerous to attempt to fill just this additional entries method in browsers that have partial support. This module only implements entries as a standalone function which will even work in browsers with no FormData support.

However, once FormData.entries is widely supported this package should be considered obsolete.

Undefined Behavior

This module makes a best effort to match the behavior of native FormData.entries. It should be possible in the future to replace calls to formDataEntries(form) with new FormData(form).entries(). However, there are some cases where this module can not fully match the native behavior.

  • If the form contains any <input type=file> elements, the behavior is considered undefined and should not be relied upon.
  • In Safari when FormData is constructed on the submit event, it will include the submitter value. This behavior does not exist in other browsers, and is not and can not be implemented in the ponyfill since the submitter element is not exposed.

Test Suite