Web/API/ConstrainDOMString

The ConstrainDOMString dictionary is used to specify a constraint for a property whose value is a string. It allows you to specify one or more exact string values from which one must be the parameter's value, or a set of ideal values which should be used if possible. You can also specify a single string (or an array of strings) which the user agent will do its best to match once all more stringent constraints have been applied.

Properties

The value of a ConstrainDOMString can be any of the following:

• A single DOMString
• An array of DOMString objects
• An object with one or both of the following properties:

exact

Either a single DOMString which must be the value of the property, or an array of DOMString objects one of which must be the property's value. If the property can't be set to one of the listed values, matching will fail.

ideal

Either a single DOMString or an array of DOMStrings specifying ideal values for the property. If possible, one of the listed values will be used, but if it's not possible, the user agent will use the closest possible match.

Specifications

Specification	Status	Comment
Media Capture and StreamsThe definition of 'ConstrainDOMString' in that specification.	Candidate Recommendation	Initial definition

Technically, ConstrainDOMString is actually based on an intermediary dictionary named ConstrainDOMStringParameters, which adds exact and ideal to DOMString. However, for the sake of documentation clarity, the intermediate type (present only because of quirks in WebIDL syntax) is ignored here.

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
ConstrainDOMString	Chrome Full support Yes	Edge Full support ≤79	Firefox Full support 50	IE No support No	Opera Full support Yes	Safari ?	WebView Android Full support Yes	Chrome Android Full support Yes	Firefox Android Full support 50	Opera Android Full support Yes	Safari iOS ?	Samsung Internet Android Full support Yes

Legend

Full support  

Full support

No support  

No support

Compatibility unknown  

Compatibility unknown

See also

• Media Capture and Streams API
• Capabilities, constraints, and settings
• MediaTrackConstraints
• MediaTrackCapabilities
• MediaTrackSupportedConstraints

ConstrainDOMString by Mozilla Contributors is licensed under CC-BY-SA 2.5.