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FormData

files/en-us/web/api/formdata/index.md

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{{APIRef("XMLHttpRequest API")}} {{AvailableInWorkers}}

The FormData interface provides a way to construct a set of key/value pairs representing form fields and their values, which can be sent using the {{domxref("Window/fetch", "fetch()")}}, {{domxref("XMLHttpRequest.send()")}} or {{domxref("navigator.sendBeacon()")}} methods. It uses the same format a form would use if the encoding type were set to "multipart/form-data".

You can also pass it directly to the {{domxref("URLSearchParams")}} constructor if you want to generate query parameters in the way a {{HTMLElement("form")}} would do if it were using simple GET submission.

An object implementing FormData can directly be used in a {{jsxref("Statements/for...of", "for...of")}} structure, instead of {{domxref('FormData.entries()', 'entries()')}}: for (const p of myFormData) is equivalent to for (const p of myFormData.entries()).

Constructor

  • {{domxref("FormData.FormData","FormData()")}}
    • : Creates a new FormData object.

Instance methods

  • {{domxref("FormData.append()")}}
    • : Appends a new value onto an existing key inside a FormData object, or adds the key if it does not already exist.
  • {{domxref("FormData.delete()")}}
    • : Deletes a key/value pair from a FormData object.
  • {{domxref("FormData.entries()")}}
    • : Returns an iterator that iterates through all key/value pairs contained in the FormData.
  • {{domxref("FormData.get()")}}
    • : Returns the first value associated with a given key from within a FormData object.
  • {{domxref("FormData.getAll()")}}
    • : Returns an array of all the values associated with a given key from within a FormData.
  • {{domxref("FormData.has()")}}
    • : Returns whether a FormData object contains a certain key.
  • {{domxref("FormData.keys()")}}
    • : Returns an iterator iterates through all keys of the key/value pairs contained in the FormData.
  • {{domxref("FormData.set()")}}
    • : Sets a new value for an existing key inside a FormData object, or adds the key/value if it does not already exist.
  • {{domxref("FormData.values()")}}
    • : Returns an iterator that iterates through all values contained in the FormData.

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also