35 lines
1.0 KiB
Markdown
35 lines
1.0 KiB
Markdown
---
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title: Remove an Item from an Array
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---
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## Remove an Item from an Array
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### Solution
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```javascript
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const immutableReducer = (state = [0,1,2,3,4,5], action) => {
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switch(action.type) {
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case 'REMOVE_ITEM':
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// don't mutate state here or the tests will fail
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return [...state.slice(0, action.index), ...state.slice(action.index + 1, state.length)];
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// or return state.slice(0, action.index).concat(state.slice(action.index + 1, state.length));
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default:
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return state;
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}
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};
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const removeItem = (index) => {
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return {
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type: 'REMOVE_ITEM',
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index
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}
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}
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const store = Redux.createStore(immutableReducer);
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```
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### Notes
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* array.slice(fromIndex, untilIndex) returns a new array
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* 1st slice from the first item's index (0 inclusive) until indexToRemove(action.index exclusive)
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* 2nd slice from item right after indexToRemove (action.index + 1 inclusive) until length (last item's index + 1 exclusive)
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* since slice returns a new array, combine both parts with [...array1, ...array2] spread operator
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* or combine them with .concat()
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