Web/API/FormData/has

The has() method of the FormData interface returns a boolean stating whether a FormData object contains a certain key.

Note: This method is available in Web Workers.

Syntax

formData.has(name);

Parameters

name: A USVString representing the name of the key you want to test for.

Returns

A Boolean.

Example

The following line creates an empty FormData object:

var formData = new FormData();

The following snippet shows the results of testing for the existence of username in the FormData object, before and after appending a username value to it with FormData.append:

formData.has('username'); // Returns false
formData.append('username', 'Chris');
formData.has('username'); // Returns true

Specifications

Specification	Status	Comment
XMLHttpRequestThe definition of 'has()' in that specification.	Living Standard

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`has`	Chrome Full support 50	Edge Full support 18	Firefox Full support 39	IE No support No	Opera Full support Yes	Safari Full support 11	WebView Android Full support Yes	Chrome Android Full support 50	Firefox Android Full support Yes	Opera Android Full support Yes	Safari iOS No support No	Samsung Internet Android Full support 5.0

Legend

Full support: Full support
No support: No support