79 lines
1.8 KiB
Markdown
79 lines
1.8 KiB
Markdown
---
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id: 587d7da9367417b2b2512b66
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title: Combine Two Arrays Using the concat Method
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challengeType: 1
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forumTopicId: 301229
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dashedName: combine-two-arrays-using-the-concat-method
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---
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# --description--
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<dfn>Concatenation</dfn> means to join items end to end. JavaScript offers the `concat` method for both strings and arrays that work in the same way. For arrays, the method is called on one, then another array is provided as the argument to `concat`, which is added to the end of the first array. It returns a new array and does not mutate either of the original arrays. Here's an example:
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```js
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[1, 2, 3].concat([4, 5, 6]);
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// Returns a new array [1, 2, 3, 4, 5, 6]
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```
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# --instructions--
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Use the `concat` method in the `nonMutatingConcat` function to concatenate `attach` to the end of `original`. The function should return the concatenated array.
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# --hints--
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Your code should use the `concat` method.
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```js
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assert(code.match(/\.concat/g));
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```
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The `first` array should not change.
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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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The `second` array should not change.
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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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`nonMutatingConcat([1, 2, 3], [4, 5])` should return `[1, 2, 3, 4, 5]`.
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```js
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assert(
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JSON.stringify(nonMutatingConcat([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 nonMutatingConcat(original, attach) {
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// Only change code below this line
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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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nonMutatingConcat(first, second);
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```
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# --solutions--
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```js
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function nonMutatingConcat(original, attach) {
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// Only change code below this line
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return original.concat(attach);
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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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nonMutatingConcat(first, second);
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```
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