Some hints about the usage of promises #4
Description
Great work. I like the plugin very much. However, unfortunately I don't have a ios device for testing.
I did spot some errors in the code, I want to point out to improve it a little bit:
device.changeStateTo(value).then( callback() )You are calling the callback, before the actions finished, because you are passing the result of the callback call to the then handler. You probably call the callback in the then handler:
device.changeStateTo(value).then( => callback() )This parses a function, that calls the callback to the handler. Which is the right way.
Further you should handle errors:
device.changeStateTo(value)
.then( => callback() )
.catch( (error) => callback(error) )
.done()catch catches an error and passes it to the callback. done throws all unhandled errors.
...
device.turnOff().then(
device.turnOn().then(
device.turnOff().then(
...The same problem here. You parsing the result of device.turnOn() to the then handler. However you want to pass a function, that calls turnOn:
...
device.turnOff().then( =>
device.turnOn().then( =>
device.turnOff().then( =>
...You can even flatten the callback chain here:
device.getState().then( (state) =>
device.turnOff()
).then( =>
device.turnOn()
).then( =>
device.turnOff()
).then( =>
device.turnOn()
).then( =>
# recover initial state
device.turnOff() if not state
)
.then( => callback() )
.catch( (error) => callback(error) )
.done()As rule of thumb: Always make sure to pass a function => ... to a then handler. Further end each chain of promise class with a .catch( (error) => callback(error) ), if you want to pass the error to a callback and with .done() to not silently discard errors.