2.9 KiB
2.9 KiB
id | title | challengeType | isRequired |
---|---|---|---|
5a24c314108439a4d403615a | Remove an Item from an Array | 6 | false |
Description
slice()
and concat()
.
Instructions
Tests
tests:
- text: The Redux store should exist and initialize with a state equal to <code>[0,1,2,3,4,5]</code>
testString: assert((function() { const initialState = store.getState(); return (Array.isArray(initialState) === true && DeepEqual(initialState, [0, 1, 2, 3, 4, 5])); })(), 'The Redux store should exist and initialize with a state equal to <code>[0,1,2,3,4,5]</code>');
- text: <code>removeItem</code> and <code>immutableReducer</code> both should be functions.
testString: assert(typeof removeItem === 'function' && typeof immutableReducer === 'function', '<code>removeItem</code> and <code>immutableReducer</code> both should be functions.');
- text: Dispatching the <code>removeItem</code> action creator should remove items from the state and should NOT mutate state.
testString: assert((function() { const initialState = store.getState(); const isFrozen = DeepFreeze(initialState); store.dispatch(removeItem(3)); const state_1 = store.getState(); store.dispatch(removeItem(2)); const state_2 = store.getState(); store.dispatch(removeItem(0)); store.dispatch(removeItem(0)); store.dispatch(removeItem(0)); const state_3 = store.getState(); return isFrozen && DeepEqual(state_1, [0, 1, 2, 4, 5]) && DeepEqual(state_2, [0, 1, 4, 5]) && DeepEqual(state_3, [5]); })(), 'Dispatching the <code>removeItem</code> action creator should remove items from the state and should NOT mutate state.');
Challenge Seed
const immutableReducer = (state = [0,1,2,3,4,5], action) => {
switch(action.type) {
case 'REMOVE_ITEM':
// don't mutate state here or the tests will fail
return
default:
return state;
}
};
const removeItem = (index) => {
return {
type: 'REMOVE_ITEM',
index
}
}
const store = Redux.createStore(immutableReducer);
Solution
const immutableReducer = (state = [0,1,2,3,4,5], action) => {
switch(action.type) {
case 'REMOVE_ITEM':
return [
...state.slice(0, action.index),
...state.slice(action.index + 1)
];
default:
return state;
}
};
const removeItem = (index) => {
return {
type: 'REMOVE_ITEM',
index
}
}
const store = Redux.createStore(immutableReducer);