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>
87 lines
2.5 KiB
Markdown
87 lines
2.5 KiB
Markdown
---
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id: 587d78b2367417b2b2512b10
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title: Remove Items Using splice()
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challengeType: 1
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forumTopicId: 301166
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dashedName: remove-items-using-splice
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---
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# --description--
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Ok, so we've learned how to remove elements from the beginning and end of arrays using `shift()` and `pop()`, but what if we want to remove an element from somewhere in the middle? Or remove more than one element at once? Well, that's where `splice()` comes in. `splice()` allows us to do just that: **remove any number of consecutive elements** from anywhere in an array.
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`splice()` can take up to 3 parameters, but for now, we'll focus on just the first 2. The first two parameters of `splice()` are integers which represent indexes, or positions, of the array that `splice()` is being called upon. And remember, arrays are *zero-indexed*, so to indicate the first element of an array, we would use `0`. `splice()`'s first parameter represents the index on the array from which to begin removing elements, while the second parameter indicates the number of elements to delete. For example:
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```js
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let array = ['today', 'was', 'not', 'so', 'great'];
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array.splice(2, 2);
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// remove 2 elements beginning with the 3rd element
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// array now equals ['today', 'was', 'great']
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```
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`splice()` not only modifies the array it's being called on, but it also returns a new array containing the value of the removed elements:
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```js
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let array = ['I', 'am', 'feeling', 'really', 'happy'];
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let newArray = array.splice(3, 2);
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// newArray equals ['really', 'happy']
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```
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# --instructions--
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We've initialized an array `arr`. Use `splice()` to remove elements from `arr`, so that it only contains elements that sum to the value of `10`.
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# --hints--
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You should not change the original line of `const arr = [2, 4, 5, 1, 7, 5, 2, 1];`.
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```js
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assert(
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__helpers.removeWhiteSpace(code).match(/constarr=\[2,4,5,1,7,5,2,1\];?/)
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);
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```
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`arr` should only contain elements that sum to `10`.
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```js
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assert.strictEqual(
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arr.reduce((a, b) => a + b),
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10
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);
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```
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Your code should utilize the `splice()` method on `arr`.
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```js
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assert(__helpers.removeWhiteSpace(code).match(/arr\.splice\(/));
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```
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The splice should only remove elements from `arr` and not add any additional elements to `arr`.
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```js
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assert(
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!__helpers.removeWhiteSpace(code).match(/arr\.splice\(\d+,\d+,\d+.*\)/g)
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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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const arr = [2, 4, 5, 1, 7, 5, 2, 1];
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// Only change code below this line
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// Only change code above this line
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console.log(arr);
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```
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# --solutions--
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```js
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const arr = [2, 4, 5, 1, 7, 5, 2, 1];
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arr.splice(1, 4);
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```
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