FormData

Table of contents

  1. 1. Syntax
  2. 2. Parameters
  3. 3. Method overview
  4. 4. Methods
    1. 4.1. append()
  5. 5. See also
  6. 6. Browser compatibility
    1. 6.1. Gecko notes
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XMLHttpRequest Level 2 adds support for the new FormData interface. FormData objects provide a way to easily construct a set of key/value pairs representing form fields and their values, which can then be easily sent using the XMLHttpRequest send() method.

It uses the same format a form would use if the encoding type were set to "multipart/form-data".

For details on how to use the FormData object, see Using FormData objects.

Syntax

new FormData ([in HTMLFormElement form])

Parameters

form
(optional) HTML Form Element <form> to send for keys/values. It will also encode file input content.

 

Method overview

void append(in DOMString name, in nsIVariant value);

Methods

append()

Appends a key/value pair to the FormData object.

void append(
  in DOMString name,
  in nsIVariant value
);
Parameters
name
The name of the field whose data is contained in value.
value
The field's value. Can be a Blob , File , or a string, if neither, the value is converted to a string.
Notes

If you specify a Blob as the data to append to the FormData object, the filename that will be reported to the server in the "Content-Disposition" header will vary from browser to browser. See the Browser compatibility section for details.

Browser compatibility

  • Desktop
  • Mobile

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 7+ 4.0 (2.0) 10+ 12+ 5+
Feature Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support 3.0 4.0 (2.0) ? ? ?

Gecko notes

Prior to Gecko 7.0 (Firefox 7.0 / Thunderbird 7.0 / SeaMonkey 2.4) , if you specified a Blob  as the data to append to the object, the filename reported in the "Content-Disposition" HTTP header was an empty string; this resulted in errors being reported by some servers. Starting in Gecko 7.0, the filename "blob" is sent.

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