在此页

• 特性
• 规范
• 浏览器兼容性
• 另请参阅
• 相关话题

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.

特性

The value of a ConstrainDOMString 可以是下列任一：

• A single DOMString
• An array of DOMString 对象
• 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 arrray of DOMString s 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.

规范

规范	状态	注释
媒体捕获和流 The definition of 'ConstrainDOMString' in that specification.	候选推荐	初始定义

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.

浏览器兼容性

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. 更新 GitHub 上的兼容性数据

	桌面						移动
	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 Yes	Edge ≤79	Firefox 50	IE No	Opera Yes	Safari ?	WebView Android Yes	Chrome Android Yes	Firefox Android 50	Opera Android Yes	Safari iOS ?	Samsung Internet Android Yes

图例

完整支持

完整支持

不支持

不支持

兼容性未知 ?

兼容性未知

另请参阅

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

元数据

• 最后修改： 2020 年 1 月 22 日

相关话题

1. Media Streams API
2. ConstrainDOMString
3. Related pages for Media Capture and Streams

   1. AudioStreamTrack
   2. BlobEvent
   3. CanvasCaptureMediaStream
   4. ConstrainBoolean
   5. ConstrainDouble
   6. ConstrainLong
   7. DoubleRange
   8. HTMLCanvasElement.captureStream()
   9. LongRange
   10. MediaDevices
   11. MediaStream
   12. MediaStreamTrack
   13. MediaStreamTrackEvent
   14. MediaTrackCapabilities
   15. MediaTrackConstraints
   16. MediaTrackSettings
   17. MediaTrackSupportedConstraints
   18. Navigator.mediaDevices
   19. NavigatorUserMedia
   20. NavigatorUserMediaError
   21. VideoStreamTrack
   22. navigator.mediaDevices.getUserMedia()