ConstrainDouble

ConstrainDouble type is used to specify a constraint for a property whose value is a double-precision floating-point number. It extends the DoubleRange dictionary (which provides the ability to specify a permitted range of property values) to also support an exact value and/or an ideal value the property should take on. Additionally, you can specify the property's value as a simple floating-point value, in which case the user agent does its best to match the value once all other more stringent constraints are met.

特性

If the value of a ConstrainDouble is an object rather than a number, it may have the properties below in addition the properties it inherits from DoubleRange .

exact
A double-precision floating-point number specifying a specific, required, value the property must have to be considered acceptable.
ideal
A double-precision floating-point number specifying a value the property would ideally have, but which can be considered optional if necessary to find a match.

规范

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

Technically, ConstrainDouble is actually based on an intermediary dictionary named ConstrainDoubleRange , which adds exact and ideal to DoubleRange , with ConstrainDouble being a type that can be either a long integer or a DoubleRange . 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

更新 GitHub 上的兼容性数据
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
ConstrainDouble 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