# typedef MediaTrackConstraints

#### package js.html

Available on HTML5

The `MediaTrackConstraints` dictionary is used to describe a set of capabilities and the value or values each can take on. A constraints dictionary is passed into `applyConstraints()` to allow a script to establish a set of exact (required) values or ranges and/or preferred values or ranges of values for the track, and the most recently-requested set of custom constraints can be retrieved by calling `getConstraints()`.

Documentation MediaTrackConstraints by Mozilla Contributors, licensed under CC-BY-SA 2.5.

See:

https://developer.mozilla.org/en-US/docs/Web/API/MediaTrackConstraints

### Properties

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`advanced:Null<Array<MediaTrackConstraintSet>>`

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`browserWindow:Null<Int>`

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`deviceId:Null<EitherType<String, EitherType<Array<String>, Dynamic>>>`

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`echoCancellation:Null<EitherType<Bool, Dynamic>>`

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`facingMode:Null<EitherType<String, EitherType<Array<String>, Dynamic>>>`

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`frameRate:Null<EitherType<Float, Dynamic>>`

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`height:Null<EitherType<Int, Dynamic>>`

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`mediaSource:Null<String>`

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`scrollWithPage:Null<Bool>`

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`viewportHeight:Null<EitherType<Int, Dynamic>>`

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`viewportOffsetX:Null<EitherType<Int, Dynamic>>`

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`viewportOffsetY:Null<EitherType<Int, Dynamic>>`

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`viewportWidth:Null<EitherType<Int, Dynamic>>`

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`width:Null<EitherType<Int, Dynamic>>`