Files

80 lines
1.6 KiB
Markdown
Raw Permalink Normal View History

---
id: 56bbb991ad1ed5201cd392ce
title: Manipulate Arrays With unshift()
challengeType: 1
videoUrl: 'https://scrimba.com/c/ckNDESv'
forumTopicId: 18239
dashedName: manipulate-arrays-with-unshift
---
# --description--
Not only can you `shift` elements off of the beginning of an array, you can also `unshift` elements to the beginning of an array i.e. add elements in front of the array.
`.unshift()` works exactly like `.push()`, but instead of adding the element at the end of the array, `unshift()` adds the element at the beginning of the array.
Example:
```js
feat(curriculum): introduce let and const earlier (#43133) * fix: move "Explore Differences Between..." to basic JS, update seed and tests * fix: resequence "Declare String Variables" * fix: move "Declare a Read-Only Variable..." to basic JS, update seed and tests * fix: revert changes to non-English "Explore Differences Between..." test text * fix: revert test strings, solutions, and seeds for non-English challenges * fix: update "Declare String Variables" description * fix: sync quotation marks in description and seed * fix: modify note in "Declare a Read-Only..." challenge * fix: update operator and compound assignment challenges * fix: update string challenges * fix: update array and array method challenges * fix: update function and scope challenges, resequence slightly * fix: "Word Blanks" solution * fix: add spacing to seed * fix: concatenating += challenge spacing * fix: appending variables to strings spacing * fix: find the length of a string spacing * fix: removed instances of removedFromMyArray = 0 * fix: switch challenges * fix: function argument and param spacing * fix: update counting cards, object challenges, and record collection * fix: finish rest of Basic JS section * fix: introducing else statements solution * fix: update spacing and wording * fix: update wording for const challenge * fix: update functional programming challenges * fix: intermediate algorithms and cert challenges * fix: revert some spacing and remove comments for fp challenge solutions * feat: add notes with links to moved let and const challenges in first two es6 challenges * fix: update es6 intro text * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * fix: concatenating strings with plus operator seed * fix: add comments back to Declare a Read-Only Variable... seed * feat: add es6 to basic javascript redirect tests for let and const challenges * fix: revert "Concatenating Strings with Plus Operator" seed * fix: move test file to cypress/integration/learn/redirects, separate redirect tests Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>
2021-10-26 01:55:58 +09:00
const ourArray = ["Stimpson", "J", "cat"];
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 16:12:12 -08:00
ourArray.shift();
ourArray.unshift("Happy");
```
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 16:12:12 -08:00
After the `shift`, `ourArray` would have the value `["J", "cat"]`. After the `unshift`, `ourArray` would have the value `["Happy", "J", "cat"]`.
# --instructions--
feat(curriculum): introduce let and const earlier (#43133) * fix: move "Explore Differences Between..." to basic JS, update seed and tests * fix: resequence "Declare String Variables" * fix: move "Declare a Read-Only Variable..." to basic JS, update seed and tests * fix: revert changes to non-English "Explore Differences Between..." test text * fix: revert test strings, solutions, and seeds for non-English challenges * fix: update "Declare String Variables" description * fix: sync quotation marks in description and seed * fix: modify note in "Declare a Read-Only..." challenge * fix: update operator and compound assignment challenges * fix: update string challenges * fix: update array and array method challenges * fix: update function and scope challenges, resequence slightly * fix: "Word Blanks" solution * fix: add spacing to seed * fix: concatenating += challenge spacing * fix: appending variables to strings spacing * fix: find the length of a string spacing * fix: removed instances of removedFromMyArray = 0 * fix: switch challenges * fix: function argument and param spacing * fix: update counting cards, object challenges, and record collection * fix: finish rest of Basic JS section * fix: introducing else statements solution * fix: update spacing and wording * fix: update wording for const challenge * fix: update functional programming challenges * fix: intermediate algorithms and cert challenges * fix: revert some spacing and remove comments for fp challenge solutions * feat: add notes with links to moved let and const challenges in first two es6 challenges * fix: update es6 intro text * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * fix: concatenating strings with plus operator seed * fix: add comments back to Declare a Read-Only Variable... seed * feat: add es6 to basic javascript redirect tests for let and const challenges * fix: revert "Concatenating Strings with Plus Operator" seed * fix: move test file to cypress/integration/learn/redirects, separate redirect tests Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>
2021-10-26 01:55:58 +09:00
Add `["Paul", 35]` to the beginning of the `myArray` variable using `unshift()`.
# --hints--
2021-02-17 15:24:53 -04:00
`myArray` should now have `[["Paul", 35], ["dog", 3]]`.
```js
assert(
(function (d) {
if (
typeof d[0] === 'object' &&
d[0][0] == 'Paul' &&
d[0][1] === 35 &&
d[1][0] != undefined &&
d[1][0] == 'dog' &&
d[1][1] != undefined &&
d[1][1] == 3
) {
return true;
} else {
return false;
}
})(myArray)
);
```
# --seed--
## --after-user-code--
```js
(function(y, z){return 'myArray = ' + JSON.stringify(y);})(myArray);
```
## --seed-contents--
```js
// Setup
feat(curriculum): introduce let and const earlier (#43133) * fix: move "Explore Differences Between..." to basic JS, update seed and tests * fix: resequence "Declare String Variables" * fix: move "Declare a Read-Only Variable..." to basic JS, update seed and tests * fix: revert changes to non-English "Explore Differences Between..." test text * fix: revert test strings, solutions, and seeds for non-English challenges * fix: update "Declare String Variables" description * fix: sync quotation marks in description and seed * fix: modify note in "Declare a Read-Only..." challenge * fix: update operator and compound assignment challenges * fix: update string challenges * fix: update array and array method challenges * fix: update function and scope challenges, resequence slightly * fix: "Word Blanks" solution * fix: add spacing to seed * fix: concatenating += challenge spacing * fix: appending variables to strings spacing * fix: find the length of a string spacing * fix: removed instances of removedFromMyArray = 0 * fix: switch challenges * fix: function argument and param spacing * fix: update counting cards, object challenges, and record collection * fix: finish rest of Basic JS section * fix: introducing else statements solution * fix: update spacing and wording * fix: update wording for const challenge * fix: update functional programming challenges * fix: intermediate algorithms and cert challenges * fix: revert some spacing and remove comments for fp challenge solutions * feat: add notes with links to moved let and const challenges in first two es6 challenges * fix: update es6 intro text * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * fix: concatenating strings with plus operator seed * fix: add comments back to Declare a Read-Only Variable... seed * feat: add es6 to basic javascript redirect tests for let and const challenges * fix: revert "Concatenating Strings with Plus Operator" seed * fix: move test file to cypress/integration/learn/redirects, separate redirect tests Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>
2021-10-26 01:55:58 +09:00
const myArray = [["John", 23], ["dog", 3]];
myArray.shift();
// Only change code below this line
feat(curriculum): introduce let and const earlier (#43133) * fix: move "Explore Differences Between..." to basic JS, update seed and tests * fix: resequence "Declare String Variables" * fix: move "Declare a Read-Only Variable..." to basic JS, update seed and tests * fix: revert changes to non-English "Explore Differences Between..." test text * fix: revert test strings, solutions, and seeds for non-English challenges * fix: update "Declare String Variables" description * fix: sync quotation marks in description and seed * fix: modify note in "Declare a Read-Only..." challenge * fix: update operator and compound assignment challenges * fix: update string challenges * fix: update array and array method challenges * fix: update function and scope challenges, resequence slightly * fix: "Word Blanks" solution * fix: add spacing to seed * fix: concatenating += challenge spacing * fix: appending variables to strings spacing * fix: find the length of a string spacing * fix: removed instances of removedFromMyArray = 0 * fix: switch challenges * fix: function argument and param spacing * fix: update counting cards, object challenges, and record collection * fix: finish rest of Basic JS section * fix: introducing else statements solution * fix: update spacing and wording * fix: update wording for const challenge * fix: update functional programming challenges * fix: intermediate algorithms and cert challenges * fix: revert some spacing and remove comments for fp challenge solutions * feat: add notes with links to moved let and const challenges in first two es6 challenges * fix: update es6 intro text * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * fix: concatenating strings with plus operator seed * fix: add comments back to Declare a Read-Only Variable... seed * feat: add es6 to basic javascript redirect tests for let and const challenges * fix: revert "Concatenating Strings with Plus Operator" seed * fix: move test file to cypress/integration/learn/redirects, separate redirect tests Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>
2021-10-26 01:55:58 +09:00
```
# --solutions--
```js
feat(curriculum): introduce let and const earlier (#43133) * fix: move "Explore Differences Between..." to basic JS, update seed and tests * fix: resequence "Declare String Variables" * fix: move "Declare a Read-Only Variable..." to basic JS, update seed and tests * fix: revert changes to non-English "Explore Differences Between..." test text * fix: revert test strings, solutions, and seeds for non-English challenges * fix: update "Declare String Variables" description * fix: sync quotation marks in description and seed * fix: modify note in "Declare a Read-Only..." challenge * fix: update operator and compound assignment challenges * fix: update string challenges * fix: update array and array method challenges * fix: update function and scope challenges, resequence slightly * fix: "Word Blanks" solution * fix: add spacing to seed * fix: concatenating += challenge spacing * fix: appending variables to strings spacing * fix: find the length of a string spacing * fix: removed instances of removedFromMyArray = 0 * fix: switch challenges * fix: function argument and param spacing * fix: update counting cards, object challenges, and record collection * fix: finish rest of Basic JS section * fix: introducing else statements solution * fix: update spacing and wording * fix: update wording for const challenge * fix: update functional programming challenges * fix: intermediate algorithms and cert challenges * fix: revert some spacing and remove comments for fp challenge solutions * feat: add notes with links to moved let and const challenges in first two es6 challenges * fix: update es6 intro text * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/concatenating-strings-with-the-plus-equals-operator.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/finding-a-remainder-in-javascript.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/global-scope-and-functions.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/iterate-through-an-array-with-a-for-loop.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/implement-map-on-a-prototype.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * Update curriculum/challenges/english/02-javascript-algorithms-and-data-structures/basic-javascript/declare-a-read-only-variable-with-the-const-keyword.md Co-authored-by: Shaun Hamilton <shauhami020@gmail.com> * fix: concatenating strings with plus operator seed * fix: add comments back to Declare a Read-Only Variable... seed * feat: add es6 to basic javascript redirect tests for let and const challenges * fix: revert "Concatenating Strings with Plus Operator" seed * fix: move test file to cypress/integration/learn/redirects, separate redirect tests Co-authored-by: Shaun Hamilton <shauhami020@gmail.com>
2021-10-26 01:55:58 +09:00
const myArray = [["John", 23], ["dog", 3]];
myArray.shift();
myArray.unshift(["Paul", 35]);
```