The sort() method sorts the elements of an array in place and returns the sorted array. The default sort order is ascending, built upon converting the elements into strings, then comparing their sequences of UTF-16 code units values.

The time and space complexity of the sort cannot be guaranteed as it depends on the implementation.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Syntax

arr .sort( [compareFunction] )

Parameters

compareFunction Optional Specifies a function that defines the sort order. If omitted, the array elements are converted to strings, then sorted according to each character's Unicode code point value. firstEl The first element for comparison. secondEl The second element for comparison.

Return value

The sorted array. Note that the array is sorted in place, and no copy is made.

Description

If compareFunction is not supplied, all non- undefined array elements are sorted by converting them to strings and comparing strings in UTF-16 code units order. For example, "banana" comes before "cherry". In a numeric sort, 9 comes before 80, but because numbers are converted to strings, "80" comes before "9" in the Unicode order. All undefined elements are sorted to the end of the array.

Note : In UTF-16, Unicode characters above \uFFFF are encoded as two surrogate code units, of the range \uD800 - \uDFFF . The value of each code unit is taken separately into account for the comparison. Thus the character formed by the surrogate pair \uD655\uDE55 will be sorted before the character \uFF3A .

If compareFunction is supplied, all non- undefined array elements are sorted according to the return value of the compare function (all undefined elements are sorted to the end of the array, with no call to compareFunction ). If a and b are two elements being compared, then:

If compareFunction(a, b) returns less than 0, sort a to an index lower than b (i.e. a comes first).

returns less than 0, sort to an index lower than (i.e. comes first). If compareFunction(a, b) returns 0, leave a and b unchanged with respect to each other, but sorted with respect to all different elements. Note: the ECMAscript standard does not guarantee this behavior, thus, not all browsers (e.g. Mozilla versions dating back to at least 2003) respect this.

returns 0, leave and unchanged with respect to each other, but sorted with respect to all different elements. Note: the ECMAscript standard does not guarantee this behavior, thus, not all browsers (e.g. Mozilla versions dating back to at least 2003) respect this. If compareFunction(a, b) returns greater than 0, sort b to an index lower than a (i.e. b comes first).

returns greater than 0, sort to an index lower than (i.e. comes first). compareFunction(a, b) must always return the same value when given a specific pair of elements a and b as its two arguments. If inconsistent results are returned, then the sort order is undefined.

So, the compare function has the following form:

function compare(a, b) { if (a is less than b by some ordering criterion) { return -1; } if (a is greater than b by the ordering criterion) { return 1; } // a must be equal to b return 0; }

To compare numbers instead of strings, the compare function can simply subtract b from a . The following function will sort the array in ascending order (if it doesn't contain Infinity and NaN ):

function compareNumbers(a, b) { return a - b; }

The sort method can be conveniently used with function expressions:

var numbers = [4, 2, 5, 1, 3]; numbers.sort(function(a, b) { return a - b; }); console.log(numbers); // [1, 2, 3, 4, 5]

ES2015 provides arrow function expressions with even shorter syntax.

let numbers = [4, 2, 5, 1, 3]; numbers.sort((a, b) => a - b); console.log(numbers); // [1, 2, 3, 4, 5]

Objects can be sorted, given the value of one of their properties.

var items = [ { name: 'Edward', value: 21 }, { name: 'Sharpe', value: 37 }, { name: 'And', value: 45 }, { name: 'The', value: -12 }, { name: 'Magnetic', value: 13 }, { name: 'Zeros', value: 37 } ]; // sort by value items.sort(function (a, b) { return a.value - b.value; }); // sort by name items.sort(function(a, b) { var nameA = a.name.toUpperCase(); // ignore upper and lowercase var nameB = b.name.toUpperCase(); // ignore upper and lowercase if (nameA < nameB) { return -1; } if (nameA > nameB) { return 1; } // names must be equal return 0; });

Examples

Creating, displaying, and sorting an array

The following example creates four arrays and displays the original array, then the sorted arrays. The numeric arrays are sorted without a compare function, then sorted using one.

var stringArray = ['Blue', 'Humpback', 'Beluga']; var numericStringArray = ['80', '9', '700']; var numberArray = [40, 1, 5, 200]; var mixedNumericArray = ['80', '9', '700', 40, 1, 5, 200]; function compareNumbers(a, b) { return a - b; } console.log('stringArray:', stringArray.join()); console.log('Sorted:', stringArray.sort()); console.log('numberArray:', numberArray.join()); console.log('Sorted without a compare function:', numberArray.sort()); console.log('Sorted with compareNumbers:', numberArray.sort(compareNumbers)); console.log('numericStringArray:', numericStringArray.join()); console.log('Sorted without a compare function:', numericStringArray.sort()); console.log('Sorted with compareNumbers:', numericStringArray.sort(compareNumbers)); console.log('mixedNumericArray:', mixedNumericArray.join()); console.log('Sorted without a compare function:', mixedNumericArray.sort()); console.log('Sorted with compareNumbers:', mixedNumericArray.sort(compareNumbers));

This example produces the following output. As the output shows, when a compare function is used, numbers sort correctly whether they are numbers or numeric strings.

stringArray: Blue,Humpback,Beluga Sorted: Beluga,Blue,Humpback numberArray: 40,1,5,200 Sorted without a compare function: 1,200,40,5 Sorted with compareNumbers: 1,5,40,200 numericStringArray: 80,9,700 Sorted without a compare function: 700,80,9 Sorted with compareNumbers: 9,80,700 mixedNumericArray: 80,9,700,40,1,5,200 Sorted without a compare function: 1,200,40,5,700,80,9 Sorted with compareNumbers: 1,5,9,40,80,200,700

Sorting non-ASCII characters

For sorting strings with non-ASCII characters, i.e. strings with accented characters (e, é, è, a, ä, etc.), strings from languages other than English, use String.localeCompare . This function can compare those characters so they appear in the right order.

var items = ['réservé', 'premier', 'communiqué', 'café', 'adieu', 'éclair']; items.sort(function (a, b) { return a.localeCompare(b); }); // items is ['adieu', 'café', 'communiqué', 'éclair', 'premier', 'réservé']

Sorting with map

The compareFunction can be invoked multiple times per element within the array. Depending on the compareFunction 's nature, this may yield a high overhead. The more work a compareFunction does and the more elements there are to sort, it may be more efficient to use map for sorting. The idea is to traverse the array once to extract the actual values used for sorting into a temporary array, sort the temporary array, and then traverse the temporary array to achieve the right order.

// the array to be sorted var list = ['Delta', 'alpha', 'CHARLIE', 'bravo']; // temporary array holds objects with position and sort-value var mapped = list.map(function(el, i) { return { index: i, value: el.toLowerCase() }; }) // sorting the mapped array containing the reduced values mapped.sort(function(a, b) { if (a.value > b.value) { return 1; } if (a.value < b.value) { return -1; } return 0; }); // container for the resulting order var result = mapped.map(function(el){ return list[el.index]; });

There is an open source library available called mapsort which applies this approach.

Specifications

Browser compatibility

The compatibility table in this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request. Update compatibility data on GitHub Desktop Mobile Server Chrome Edge Firefox Internet Explorer Opera Safari Android webview Chrome for Android Firefox for Android Opera for Android Safari on iOS Samsung Internet Node.js sort Chrome Full support 1 Edge Full support 12 Firefox Full support 1 IE Full support 5.5 Opera Full support 4 Safari Full support 1 WebView Android Full support 1 Chrome Android Full support 18 Firefox Android Full support 4 Opera Android Full support 10.1 Safari iOS Full support 1 Samsung Internet Android Full support 1.0 nodejs Full support 0.1.100 Stable sorting Chrome Full support 70 Edge Full support 79 Firefox Full support 3 IE No support No Opera Full support 57 Safari Full support 10.1 WebView Android Full support 70 Chrome Android Full support 70 Firefox Android Full support 4 Opera Android Full support 49 Safari iOS Full support 10.3 Samsung Internet Android Full support 10.0 nodejs Full support 12.0.0 Legend Full support Full support No support No support

See also