87 lines
2.3 KiB
Markdown
87 lines
2.3 KiB
Markdown
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---
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id: 587d78b2367417b2b2512b0f
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title: Remove Items from an Array with pop() and shift()
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challengeType: 1
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forumTopicId: 301165
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dashedName: remove-items-from-an-array-with-pop-and-shift
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---
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# --description--
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Both `push()` and `unshift()` have corresponding methods that are nearly functional opposites: `pop()` and `shift()`. As you may have guessed by now, instead of adding, `pop()` *removes* an element from the end of an array, while `shift()` removes an element from the beginning. The key difference between `pop()` and `shift()` and their cousins `push()` and `unshift()`, is that neither method takes parameters, and each only allows an array to be modified by a single element at a time.
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Let's take a look:
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```js
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let greetings = ['whats up?', 'hello', 'see ya!'];
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greetings.pop();
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```
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`greetings` would have the value `['whats up?', 'hello']`.
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```js
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greetings.shift();
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```
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`greetings` would have the value `['hello']`.
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We can also return the value of the removed element with either method like this:
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```js
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let popped = greetings.pop();
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```
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`greetings` would have the value `[]`, and `popped` would have the value `hello`.
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# --instructions--
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We have defined a function, `popShift`, which takes an array as an argument and returns a new array. Modify the function, using `pop()` and `shift()`, to remove the first and last elements of the argument array, and assign the removed elements to their corresponding variables, so that the returned array contains their values.
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# --hints--
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`popShift(["challenge", "is", "not", "complete"])` should return `["challenge", "complete"]`
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```js
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assert.deepEqual(popShift(['challenge', 'is', 'not', 'complete']), [
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'challenge',
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'complete'
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]);
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```
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The `popShift` function should utilize the `pop()` method
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```js
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assert.notStrictEqual(popShift.toString().search(/\.pop\(/), -1);
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```
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The `popShift` function should utilize the `shift()` method
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```js
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assert.notStrictEqual(popShift.toString().search(/\.shift\(/), -1);
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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 popShift(arr) {
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let popped; // Change this line
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let shifted; // Change this line
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return [shifted, popped];
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}
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console.log(popShift(['challenge', 'is', 'not', 'complete']));
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```
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# --solutions--
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```js
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function popShift(arr) {
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let popped = arr.pop(); // Change this line
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let shifted = arr.shift(); // Change this line
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return [shifted, popped];
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}
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```
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