files/en-us/web/api/mediatracksupportedconstraints/latency/index.md
{{APIRef("Media Capture and Streams")}}
The {{domxref("MediaTrackSupportedConstraints")}} dictionary's latency property is a read-only Boolean value which is present (and set to true) in the object returned by {{domxref("MediaDevices.getSupportedConstraints()")}} if and only if the {{Glossary("user agent")}} supports the latency constraint.
If the constraint isn't supported, it's not included in the list, so this value will never be false.
You can access the supported constraints dictionary by calling navigator.mediaDevices.getSupportedConstraints().
This property is present in the dictionary (and its value is always true) if the user agent supports the latency constraint.
If the property isn't present, this property is missing from the supported constraints dictionary, and you'll get {{jsxref("undefined")}} if you try to look at its value.
<div id="result"></div>
#result {
font:
14px "Arial",
sans-serif;
}
const result = document.getElementById("result");
const supported = navigator.mediaDevices.getSupportedConstraints().latency;
result.textContent = supported ? "Supported!" : "Not supported!";
{{ EmbedLiveSample('Examples', 600, 80) }}
{{Specifications}}
{{Compat}}