Created
July 30, 2018 01:00
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const createKeyEventObserver = () => { | |
const PRESS_THRESHOULD_MS = 500 | |
const LONG_PRESS_TIME_MS = 1500 | |
const keyDowns = fromEvent(document.body, 'keydown') | |
const keyUps = fromEvent(document.body, 'keyup') | |
const source = keyDowns | |
.pipe( | |
merge(keyUps), | |
distinctUntilChanged((a, b) => a.type === b.type && a.key === b.key), | |
map(({ key, type}) => ({ key, type })), | |
scan((acc, { type, key }) => ( | |
type === 'keydown' ? [ | |
...acc, key | |
] : acc.filter(item => item !== key) | |
), []), | |
scan((prev, state) => ({ | |
operation: state.length > prev.state.length ? 'add' : 'remove', | |
state, | |
}), { state: [] }), | |
mergeMap((item) => ( | |
item.operation === 'remove' | |
? of(0, PRESS_THRESHOULD_MS).pipe( | |
delayWhen(time => timer(time)), | |
map( value => ( | |
value !== 0 ? { | |
keyUpState: [...item.state] | |
} : item | |
)) | |
) | |
: of({ | |
...item, | |
keyUpState: [...item.state] | |
}) | |
)), | |
scan((prev, current) => ( | |
current.keyUpState ? current : { | |
...current, | |
keyUpState: prev ? prev.keyUpState : [] | |
} | |
)), | |
filter(item => item.operation), | |
) | |
const allKeyUpSource = source.pipe( | |
startWith({ | |
state: [] | |
}), | |
filter(item => ( | |
item.state.length === 0 | |
)), | |
map(_ => ({ | |
event: 'allkeyup' | |
})), | |
) | |
const pressSource = source.pipe( | |
filter(({ operation, state, keyUpState }) => ( | |
operation === 'remove' && state.length === 0 && keyUpState.length !== 0 | |
)), | |
map(val => ({ | |
event: 'press', | |
keys: val.keyUpState | |
})), | |
) | |
const longPressSource = source.pipe( | |
filter(item => item.state.length !== 0), | |
switchMap( | |
item => timer(LONG_PRESS_TIME_MS).pipe( | |
map(_ => ({ | |
event: 'longpress', | |
keys: item.state | |
})) | |
) | |
), | |
) | |
const eventSource = allKeyUpSource.pipe( | |
mergeMap( | |
(item) => pressSource.pipe( | |
merge(longPressSource), | |
first() | |
) | |
), | |
tap(val => console.log(val)), | |
) | |
return eventSource | |
} |
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