FormData

The FormData interface provides 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".

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 (var p of myFormData) is equivalent to for (var p of myFormData.entries()).

Constructor

FormData()

Creates a new FormData object.

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 allowing to go through all key/value pairs contained in this object.

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 a boolean stating whether a FormData object contains a certain key.

FormData.keys()

Returns an iterator allowing to go through all keys of the key/value pairs contained in this object.

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 allowing to go through all values contained in this object.

Specifications

Browser compatibility

See also

• XMLHTTPRequest
• Using XMLHttpRequest
• Using FormData objects
• <form>