Get and Set Volume with JavaScript

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The <audio> and <video> tags provide a wealth more functionality than most people know. For instance, did you know that you could detect supported video formats and audio formats using a few JavaScript tricks?  It got me to thinking about the possibilities of detecting system volume with JavaScript in the browser.

I hate to be a buzzkill but unfortunately JavaScript doesn't provide direct access to the system volume but you can, using <audio> and/or <video> elements, programmatically set and get the volume level.

// Getting volume level
const volume = document.querySelector("video").volume; // 1 

// Setting volume level
document.querySelector("video").volume = 0.5;  // set volume to 50%

You can also listen for volume changes with the "onvolumechange" event:

document.querySelector("video").addEventListener("onvolumechange", e => {
    // Change your custom control UI
});

It makes sense that you can't set system volume level from a random JavaScript snippet in a browser but I had a slight hope you could retrieve that level.  Setting volume with JavaScript for a given piece of media is relative to system volume level but hey -- at least we get to create custom controls for those elements with .volume settings!

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Discussion

  1. Great article! I would be curious on if this would be possible in node.js since it does have access to system files

  2. Tim

    Except on iOS, where the volume has always been read only. Apparently Apple didn’t want applications to have access to the volume knob even though the system volume is under user control via hardware.

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