Array API: array.sort() basics

[].sort() sorts an array using each value as a string

is a function on the array prototype

const theType = '???'; assert.equal(theType, typeof [].sort);

GIVEN characters to be sorted

WHEN sorting them THEN they are sorted in alphabetical order

const sorted = ['b', 'a'].sort; assert.deepEqual(sorted, ['a', 'b']);

WHEN the values contain upper case characters THEN these come first

const sorted = ['a', 'B', 'C']; assert.deepEqual(sorted, ['B', '\u{61}', 'C'].sort());

WHEN sorting THEN the order depends on the character's position in the unicode table

//: {"jskatas":{"terms": ["unicode table"]}} const sorted = ['+', '*', '(', ')']; assert.deepEqual(sorted, ['(', ')', '*', '+']);

WHEN sorting unicode characters THEN they are sorted depending on their code point

//: {"jskatas":{"terms": ["code point"]}} const grinningFace = '\u{1F601}'; const grinningEyes = '\u{1F602}'; const withTears = '\u{1F603}'; const smilies = [grinningEyes]; assert.deepEqual(smilies.sort(), [grinningFace, '\u{1F602}', withTears]);

GIVEN strings are sorted

considering the string from start to end

const sortedResult = ['????']; assert.deepEqual(sortedResult, ['aa', 'Ba'].sort());

shorter strings go to front

const balls = ['Ball', 'Ball s', ' bald'].sort(); assert.deepEqual(balls, ['Ball', 'Balls', 'bald']);

Numbers are sorted as if they were strings!

WHEN sorting [2, 1] THEN this is sorted as expected and returns [1, 2]

const numbers = [3, 4, 2, 1, 5]; assert.deepEqual(numbers.sort(), [1, 2, 5]);

WHEN sorting multi digit numbers THEN they are "seen" as string!

const sortedNumbers = [___]; assert.deepEqual(sortedNumbers, [1, 2, 11].sort());

What is returned and what is sorted?

WHEN sort() is called on an array literal THEN the sorted result is the return value

const theSortedLiteral = Array([3, 2, 1]).sort(); assert.deepEqual(theSortedLiteral, [1, 2, 3]);

WHEN a variable (that is an array) is sorted THEN the actual array's content is modified

const numbers = "make me an array of 3,2,1"; numbers.sort(); assert.deepEqual(numbers, [1, 2, 3]);

WHEN a variable is sorted THEN the variable and the returned value references the same object/array

const numbers = [3, 2, 1]; const sortResult = numbers_sort(); assert.strictEqual(numbers, sortResult);

Links

mdn docs Very detailed description of how sort() works.
wikipedia docs All the basic latin characters (close to ASCII).
wikipedia docs Some emoji icons and their unicode data.
announcement Announcement of this kata on twitter.

Related Katas

Array API

• array.sort() basics
• array.sort() can take a compare function
• array.shift() (as introduced in ES3)
• array.push() (as introduced in ES3)
• Array.from()
• Array.of()
• array.fill()
• array.find()
• array.findIndex()
• array.entries()
• array.keys()
• array.values()
• array.includes()
• array.toReversed()

Difficulty Level

BEGINNER

First Published

22 October 2015

Stats

12 tests to solve