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.




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


A Boolean.


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


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

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 50.0 39.0 (39.0) No support (Yes) No support
Available in web workers 50.0 39.0 (39.0) No support (Yes) No support
Feature Android Android Webview Firefox Mobile (Gecko) Firefox OS (Gecko) IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support 50.0 (Yes) (Yes) No support


No support 50.0
Available in web workers No support 50.0 (Yes) (Yes) No support (Yes) No support 50.0

See also

Document Tags and Contributors

 Contributors to this page: jpmedley, Jonathan_Watt, Jeremie, chrisdavidmills, kscarfone
 Last updated by: jpmedley,