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camperbot 5075f14248 chore(i18n,learn): processed translations (#41378 )

* chore(i8n,learn): processed translations

* Update curriculum/challenges/chinese/01-responsive-web-design/applied-visual-design/use-the-u-tag-to-underline-text.md

Co-authored-by: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

Co-authored-by: Crowdin Bot <support+bot@crowdin.com>
Co-authored-by: Nicholas Carrigan (he/him) <nhcarrigan@gmail.com>
Co-authored-by: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

2021-03-05 07:43:24 -08:00

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id, title, challengeType, forumTopicId, dashedName

id	title	challengeType	forumTopicId	dashedName
5a24c314108439a4d403615a	从数组中删除项目	6	301447	remove-an-item-from-an-array

--description--

是时候练习从数组中删除项目了。扩展运算符也可以在这里使用。其他有用的JavaScript方法包括 slice() 和 concat()。

--instructions--

reducer 和 action creator 被修改为根据项目的索引从数组中删除一个项目。完成编写 reducer 以便返回一个新的状态数组，并删除特定索引处的项目。

--hints--

Redux store 应该存在并初始化一个 [0,1,2,3,4,5] 的状态。

assert(
  (function () {
    const initialState = store.getState();
    return (
      Array.isArray(initialState) === true &&
      DeepEqual(initialState, [0, 1, 2, 3, 4, 5])
    );
  })()
);

removeItem 和 immutableReducer 都应该是一个函数。

assert(
  typeof removeItem === 'function' && typeof immutableReducer === 'function'
);

dispatch removeItem action creator 应该从 state 中删除项目，不应该改变 state。

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])
    );
  })()
);

--seed--

--seed-contents--

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);

--solutions--

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);

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