Yoctopuce Yocto-Display, User Manual

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22. High-level API Reference
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YAnButton
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isOnline_async()
Checks if the analog input is currently reachable, without raising any error (asynchronous version).
js
function isOnline_async( callback , context )
If there is a cached value for the analog input in cache, that has not yet expired, the device is
considered reachable. No exception is raised if there is an error while trying to contact the device
hosting the requested function.
This asynchronous version exists only in Javascript. It uses a callback instead of a return value in order
to avoid blocking the Javascript virtual machine.
Parameters :
callback callback function that is invoked when the result is known. The callback function receives three
arguments: the caller-specific context object, the receiving function object and the boolean result
context caller-specific object that is passed as-is to the callback function
Returns :
nothing : the result is provided to the callback.