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August 29, 2015 14:23
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const INCREMENT = 'INCREMENT', DECREMENT = 'DECREMENT'; | |
function reducer(state, action) { | |
switch (action.type) { | |
case INCREMENT: | |
return state + 1; | |
case DECREMENT: | |
return state - 1; | |
} | |
} | |
function* states(reducer, initialState) { | |
while (true) { | |
// yield returns an argument that was passed in .next() | |
initialState = reducer(initialState, yield initialState); | |
} | |
} | |
var appState = states(reducer, 0); | |
// first .next() call ignores passed arguments | |
// (or I didn't use generator correctly) | |
console.log(appState.next()); | |
// each time iterator will update the state with provided action and return new state | |
console.log(appState.next({ type: INCREMENT })); | |
console.log(appState.next({ type: INCREMENT })); | |
console.log(appState.next({ type: INCREMENT })); | |
console.log(appState.next({ type: DECREMENT })); |
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21 - 22 is fine, that's the way generators are meant to work, it will run the generator to the first
yield
and then pause it. Next time you callnext
it picks up from there hence a passed in argument now being used.