The requestMIDIAccess()
method of the Navigator
interface returns a Promise
representing a request for access to MIDI devices on a user's system. This method is part of the Web MIDI API, which provides a means for accessing, enumerating, and manipulating MIDI devices.
This method may prompt the user for access to MIDI devices available to their system, or it may use a previously established preference to grant or deny access. If permission is granted then the Promise
resolves and a MIDIAccess
object is returned.
requestMIDIAccess()
requestMIDIAccess(MIDIOptions)
A Promise
that resolves with a MIDIAccess
object.
Access to the API is subject to the following constraints:
- The method must be called in a secure context.
- Access may be gated by the
midi
HTTP Permission Policy. - The user must explicitly grant permission to use the API though a user-agent specific mechanism, or have previously granted permission. Note that if access is denied by a permission policy it cannot be granted by a user permission.
The permission status can be queried using the Permissions API method navigator.permissions.query()
, passing a permission descriptor with the midi
permission and (optional) sysex
property:
navigator.permissions.query({ name: "midi", sysex: true }).then((result) => {
if (result.state === "granted") {
} else if (result.state === "prompt") {
}
});
In the following example, the Navigator.requestMIDIAccess()
method returns the MIDIAccess
object, which gives access to information about the input and output MIDI ports.
navigator.requestMIDIAccess().then((access) => {
const inputs = access.inputs.values();
const outputs = access.outputs.values();
});