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Nicholas Carrigan (he/him) 7117919d36 chore(learn): audit javascript algorithms and data structures (#41092)
* chore(learn): audit basic algorithm scripting

* chore(learn): audit basic data structures

* chore(learn): audit basic javascript

* chore(learn): audit debugging

* chore(learn): audit es6

* chore(learn): audit functional programming

* chore(learn): audit intermidate algorithms

* chore(learn): audit js projects

* chore(learn): audit object oriented programming

* chore(learn): audit regex

* fix(learn): remove stray .

* fix(learn): string to code

* fix(learn): missed some

* fix(learn): clarify strings

Based on Randy's feedback, clarifies string instances where quotes
were removed in favour of back ticks.

* fix: apply suggestions - thanks Randy! :)

Co-authored-by: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

* fix: non-suggestion comments

* chore(learn): remove comments from codes

Removes the comments from the description and instruction code
blocks to ensure that all relevant information is translatable.

* fix: Apply suggestions from code review

Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>

* fix: revert crowdin fix

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-algorithm-scripting/mutations.md

Co-authored-by: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

* fix: Apply suggestions from code review

Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/es6/use-destructuring-assignment-to-assign-variables-from-arrays.md

Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>

* fix: Apply suggestions from code review

Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>

* chore: change voice

* fix: Christopher Nolan

* fix: expressions would evaluate

* fix: will -> would

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/object-oriented-programming/add-methods-after-inheritance.md

Co-authored-by: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

* fix: to work to push

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-with-javascript-for-loops.md

Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>

* Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/object-oriented-programming/add-methods-after-inheritance.md

Co-authored-by: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>

Co-authored-by: Randell Dawson <5313213+RandellDawson@users.noreply.github.com>
Co-authored-by: Shaun Hamilton <51722130+ShaunSHamilton@users.noreply.github.com>
Co-authored-by: Oliver Eyton-Williams <ojeytonwilliams@gmail.com>
2021-03-02 17:12:12 -07:00

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---
id: 587d78b2367417b2b2512b0f
title: Remove Items from an Array with pop() and shift()
challengeType: 1
forumTopicId: 301165
dashedName: remove-items-from-an-array-with-pop-and-shift
---
# --description--
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.
Let's take a look:
```js
let greetings = ['whats up?', 'hello', 'see ya!'];
greetings.pop();
```
`greetings` would have the value `['whats up?', 'hello']`.
```js
greetings.shift();
```
`greetings` would have the value `['hello']`.
We can also return the value of the removed element with either method like this:
```js
let popped = greetings.pop();
```
`greetings` would have the value `[]`, and `popped` would have the value `hello`.
# --instructions--
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.
# --hints--
`popShift(["challenge", "is", "not", "complete"])` should return `["challenge", "complete"]`
```js
assert.deepEqual(popShift(['challenge', 'is', 'not', 'complete']), [
'challenge',
'complete'
]);
```
The `popShift` function should utilize the `pop()` method
```js
assert.notStrictEqual(popShift.toString().search(/\.pop\(/), -1);
```
The `popShift` function should utilize the `shift()` method
```js
assert.notStrictEqual(popShift.toString().search(/\.shift\(/), -1);
```
# --seed--
## --seed-contents--
```js
function popShift(arr) {
let popped; // Change this line
let shifted; // Change this line
return [shifted, popped];
}
console.log(popShift(['challenge', 'is', 'not', 'complete']));
```
# --solutions--
```js
function popShift(arr) {
let popped = arr.pop(); // Change this line
let shifted = arr.shift(); // Change this line
return [shifted, popped];
}
```