Support for the Web MIDI API has been added to Chrome Canary since early 2013.

Why then, when I type requestMIDIAccess in the JavaScript console and hit enter, do I get "ReferenceError: requestMIDIAccess is not defined"?

According to official documentation, it should be a defined function.

What gives?

Support for the Web MIDI API has been added to Chrome Canary since early 2013.

Why then, when I type requestMIDIAccess in the JavaScript console and hit enter, do I get "ReferenceError: requestMIDIAccess is not defined"?

According to official documentation, it should be a defined function.

What gives?

• javascript
• google-chrome
• web-midi

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2 Answers 2

Sorted by: Reset to default 8

The Web MIDI API is available by default only in Chrome versions 43 and newer.

In earlier versions it is not enabled by default, but can be enabled as an experimental feature flag. In Chrome, load the special URL chrome://flags and search within the page for "Enable Web MIDI API".

The options on the flags page require the browser to be restarted before they will take effect. The features hidden behind these flags are in an experimental state and are subject to change at any time, so the API in older versions may differ from what is available in Chrome 43.

Note also that the requestMIDIAccess function is a method of window.navigator, not directly of window. Therefore you need to call it as navigator.requestMIDIAccess.

Also note that after you plug-in a new MIDI device, you may need to quit and restart Chrome. It does not seem to handle dynamic adjustment of the device list.