The 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.
Properties
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.
Specifications
| Specification | Status | Comment |
|---|---|---|
| Media Capture and Streams The definition of 'ConstrainDouble' in that specification. |
Editor's Draft | Initial definition |
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.
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Microsoft Edge | Opera | Safari (WebKit) |
|---|---|---|---|---|---|---|
| Basic support | (Yes) | 50 (50) | No support | ? | No support | ? |
| Feature | Android | Android Webview | Firefox Mobile (Gecko) | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android |
|---|---|---|---|---|---|---|---|
| Basic support | ? | (Yes) | 50.0 (50) | No support | No support | ? | (Yes) |