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ElementInternals: setFormValue() method
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since March 2023.
The setFormValue() method of the ElementInternals interface sets the element's submission value and state, communicating these to the user agent.
js
setFormValue(value)
setFormValue(value, state)
value-
A File, a string, or a FormData as the value to be submitted to the server.
state Optional-
A File, a string, or a FormData representing the input made by the user.
This allows the application to re-display the information that the user submitted, in the form that they submitted it, if required.
Note:
In general, state is used to pass information specified by a user, the value is suitable for submission to a server, post sanitization.
For example, if a custom element asked a user to submit a date, the user might enter "3/15/2019".
This would be the state.
The server expects a date format of 2019-03-15, the date in this format would be passed as the value.
NotSupportedError DOMException-
Thrown if the element does not have its formAssociated property set to true.
In the following example, a checkbox custom element sets on as the value to send to the server, and checked as the state.
js
this.internals_.setFormValue("on", "checked");