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FormData: has() method

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨October 2018⁩.

Note: This feature is available in Web Workers.

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

Syntax

has(name)

Parameters

name

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

Return value

true if a key of FormData matches the specified name. Otherwise, false.

Examples

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

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

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Opera Safari Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet WebView Android WebView on iOS
has 50 18 39 37 11.1 50 39 37 11.3 5.0 50 11.3

See also

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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/FormData/has