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.
has(name)
nameA string representing the name of the key you want to test for.
true if a key of FormData matches the specified name. Otherwise, false.
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
| Specification |
|---|
| XMLHttpRequest> # dom-formdata-has> |
| 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 |
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https://developer.mozilla.org/en-US/docs/Web/API/FormData/has