84 lines
2.9 KiB
Markdown
84 lines
2.9 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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---
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## Description
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<section id='description'>
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Ok, so we've learned how to remove elements from the beginning and end of arrays using <code>shift()</code> and <code>pop()</code>, 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 <code>splice()</code> comes in. <code>splice()</code> allows us to do just that: <strong>remove any number of consecutive elements</strong> from anywhere in an array.
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<code>splice()</code> can take up to 3 parameters, but for now, we'll focus on just the first 2. The first two parameters of <code>splice()</code> are integers which represent indexes, or positions, of the array that <code>splice()</code> is being called upon. And remember, arrays are <em>zero-indexed</em>, so to indicate the first element of an array, we would use <code>0</code>. <code>splice()</code>'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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<code>splice()</code> 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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</section>
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## Instructions
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<section id='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 <code>10</code>.
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: You should not change the original line of <code>const arr = [2, 4, 5, 1, 7, 5, 2, 1];</code>.
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testString: assert(code.replace(/\s/g, '').match(/constarr=\[2,4,5,1,7,5,2,1\];?/));
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- text: <code>arr</code> should only contain elements that sum to <code>10</code>.
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testString: assert.strictEqual(arr.reduce((a, b) => a + b), 10);
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- text: Your code should utilize the <code>splice()</code> method on <code>arr</code>.
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testString: assert(code.replace(/\s/g, '').match(/arr\.splice\(/));
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- text: The splice should only remove elements from <code>arr</code> and not add any additional elements to <code>arr</code>.
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testString: assert(!code.replace(/\s/g, '').match(/arr\.splice\(\d+,\d+,\d+.*\)/g));
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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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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</div>
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</section>
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## Solution
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<section id='solution'>
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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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</section>
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