ee1e8abd87
* feat(tools): add seed/solution restore script * chore(curriculum): remove empty sections' markers * chore(curriculum): add seed + solution to Chinese * chore: remove old formatter * fix: update getChallenges parse translated challenges separately, without reference to the source * chore(curriculum): add dashedName to English * chore(curriculum): add dashedName to Chinese * refactor: remove unused challenge property 'name' * fix: relax dashedName requirement * fix: stray tag Remove stray `pre` tag from challenge file. Signed-off-by: nhcarrigan <nhcarrigan@gmail.com> Co-authored-by: nhcarrigan <nhcarrigan@gmail.com>
89 lines
1.9 KiB
Markdown
89 lines
1.9 KiB
Markdown
---
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id: 587d7da9367417b2b2512b67
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title: 使用 concat 而不是 push 将元素添加到数组的末尾
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challengeType: 1
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forumTopicId: 301226
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dashedName: add-elements-to-the-end-of-an-array-using-concat-instead-of-push
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---
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# --description--
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函数式编程就是创建和使用具有不变性的函数。
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上一个挑战介绍了`concat`方法，这是一种在不改变原始数组的前提下，将数组组合成新数组的方法。将`concat`方法与`push`方法做比较，`Push`将元素添加到调用它的数组的末尾，这样会改变该数组。举个例子：
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```js
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var arr = [1, 2, 3];
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arr.push([4, 5, 6]);
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// arr is changed to [1, 2, 3, [4, 5, 6]]
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// Not the functional programming way
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```
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`Concat`方法可以将新项目添加到数组末尾，而不产生任何变化。
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# --instructions--
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修改`nonMutatingPush`函数，用`concat`替代`push`将`newItem`添加到`original`末尾，该函数应返回一个数组。
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# --hints--
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应该使用`concat`方法。
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```js
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assert(code.match(/\.concat/g));
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```
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不能使用`push`方法。
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```js
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assert(!code.match(/\.push/g));
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```
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不能改变`first`数组。
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```js
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assert(JSON.stringify(first) === JSON.stringify([1, 2, 3]));
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```
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不能改变`second`数组。
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```js
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assert(JSON.stringify(second) === JSON.stringify([4, 5]));
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```
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`nonMutatingPush([1, 2, 3], [4, 5])`应返回`[1, 2, 3, 4, 5]`。
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```js
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assert(
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JSON.stringify(nonMutatingPush([1, 2, 3], [4, 5])) ===
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JSON.stringify([1, 2, 3, 4, 5])
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);
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```
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# --seed--
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## --seed-contents--
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```js
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function nonMutatingPush(original, newItem) {
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// Only change code below this line
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return original.push(newItem);
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// Only change code above this line
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}
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var first = [1, 2, 3];
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var second = [4, 5];
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nonMutatingPush(first, second);
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```
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# --solutions--
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```js
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function nonMutatingPush(original, newItem) {
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return original.concat(newItem);
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}
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var first = [1, 2, 3];
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var second = [4, 5];
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nonMutatingPush(first, second);
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```
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