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FormData

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 fetch(), XMLHttpRequest.send() or 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 URLSearchParams constructor if you want to generate query parameters in the way a <form> would do if it were using simple GET submission.

An object implementing FormData can directly be used in a for...of structure, instead of entries(): for (const p of myFormData) is equivalent to for (const p of myFormData.entries()).

Note: This feature is available in Web Workers.

Constructor

FormData(): Creates a new FormData object.

Instance methods

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

Specifications

Specification
XMLHttpRequest Standard # interface-formdata

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`@@iterator`	50	18	44	No	37	11.1	50	50	44	37	11.3	5.0
`FormData`	5	12	4	10	12	5	3	18	4	12	5	1.0
`FormData`	5	12	4 Before Firefox 7, specifying a `Blob` as the data to append to the object, the filename reported in the `Content-Disposition` HTTP header was an empty string, resulting in errors on some servers. Starting with Firefox 7, the filename `blob` is sent.	10	12	5	3 XHR in Android 4.0 sends empty content for `FormData` with `blob`.	18	4 Before Firefox 7, specifying a `Blob` as the data to append to the object, the filename reported in the `Content-Disposition` HTTP header was an empty string, resulting in errors on some servers. Starting with Firefox 7, the filename `blob` is sent.	12	5	1.0
`append`	5	12	4 Before Firefox 7, specifying a `Blob` as the data to append to the object, the filename reported in the `Content-Disposition` HTTP header was an empty string, resulting in errors on some servers. Starting with Firefox 7, the filename `blob` is sent.	10 With the "Include local directory pass when uploading files to a server" option enabled, IE will change the filename inside the `Blob` on the fly. To have direct control of the sent filename, the developer should send the filename as the third parameter value, i.e. `formData.append(name, value, filename)`.	12	5	3 XHR in Android 4.0 sends empty content for `FormData` with `blob`.	18	4 Before Firefox 7, specifying a `Blob` as the data to append to the object, the filename reported in the `Content-Disposition` HTTP header was an empty string, resulting in errors on some servers. Starting with Firefox 7, the filename `blob` is sent.	12	5	1.0
`delete`	50	18	39	No	37	11.1	50	50	39	37	11.3	5.0
`entries`	50	18	44	No	37	11.1	50	50	44	37	11.3	5.0
`forEach`	50	18	47	No	37	11.1	50	50	47	37	11.3	5.0
`get`	50	18	39	No	37	11.1	50	50	39	37	11.3	5.0
`getAll`	50	18	39	No	37	11.1	50	50	39	37	11.3	5.0
`has`	50	18	39	No	37	11.1	50	50	39	37	11.3	5.0
`keys`	50	18	44	No	37	11.1	50	50	44	37	11.3	5.0
`set`	50	18	39	No	37	11.1	50	50	39	37	11.3	5.0
`values`	50	18	44	No	37	11.1	50	50	44	37	11.3	5.0
`worker_support`	50	79	39	No	37	13.1	50	50	39	37	13.4	5.0

Constructor

Instance methods

Specifications

Browser compatibility

See also