String.prototype.split()

The split() method turns a String into an array of strings, by separating the string at each instance of a specified separator string.

Syntax

str.split([separator[, limit]])

Parameters

  • If separator contains multiple characters, that entire character sequence must be found in order to split.
  • If separator is omitted or does not occur in str, the returned array contains one element consisting of the entire string.
  • If separator appears at the beginning or end of the string, or both, the array begins, ends, or both begins and ends, respectively, with an empty string.
  • If separator is an empty string (""), str is converted to an array of each of its UTF-16 “characters”.

Warning: When the empty string ("") is used as a separator, the string is not split by user-perceived characters (grapheme clusters) or unicode characters (codepoints), but by UTF-16 codeunits. This destroys surrogate pairs. See “How do you get a string to a character array in JavaScript?” on StackOverflow.

separator Optional
The string where each split should occur. Can be a string or a regular expression.
limit Optional

A non-negative integer limiting the number of splits. If provided, splits the string at each occurrence of the specified separator, but stops when limit entries have been placed in the array.

  • It may contain fewer entries than limit if the end of the string is reached before the limit is reached. The leftover text is not returned in the new array.
  • If limit is 0, no splitting is performed.

Return value

An Array of strings, split at each point where the separator occurs in the given string.

Description

When found, separator is removed from the string and the substrings are returned in an array.

If separator is a regular expression with capturing parentheses, then each time separator matches, the results (including any undefined results) of the capturing parentheses are spliced into the output array.

The separator is an array

Note: if the separator is an array, then that Array is coerced to a String and used as a separator.

Examples

Using split()

Note: When the string is empty, split() returns an array containing one empty string, rather than an empty array. If the string and separator are both empty strings, an empty array is returned.
const myString = '';
const splits = myString.split();

console.log(splits); 

// ↪ [""]

The following example defines a function that splits a string into an array of strings using the specified separator. After splitting the string, the function logs messages indicating the original string (before the split), the separator used, the number of elements in the array, and the individual array elements.

function splitString(stringToSplit, separator) {
  const arrayOfStrings = stringToSplit.split(separator);

  console.log('The original string is: ', stringToSplit);
  console.log('The separator is: ', separator);
  console.log('The array has ', arrayOfStrings.length, ' elements: ', arrayOfStrings.join(' / '));
}

const tempestString = 'Oh brave new world that has such people in it.';
const monthString = 'Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec';

const space = ' ';
const comma = ',';

splitString(tempestString, space);
splitString(tempestString);
splitString(monthString, comma);

This example produces the following output:

The original string is: "Oh brave new world that has such people in it."
The separator is: " "
The array has 10 elements: Oh / brave / new / world / that / has / such / people / in / it.

The original string is: "Oh brave new world that has such people in it."
The separator is: "undefined"
The array has 1 elements: Oh brave new world that has such people in it.

The original string is: "Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec"
The separator is: ","
The array has 12 elements: Jan / Feb / Mar / Apr / May / Jun / Jul / Aug / Sep / Oct / Nov / Dec

Removing spaces from a string

In the following example, split() looks for 0 or more spaces followed by a semicolon followed by 0 or more spaces and, when found, removes the spaces and the semicolon from the string. nameList is the array returned as a result of split().

const names = 'Harry Trump ;Fred Barney; Helen Rigby ; Bill Abel ;Chris Hand ';

console.log(names);

const re = /\s*(?:;|$)\s*/;
const nameList = names.split(re);

console.log(nameList);

This logs two lines; the first line logs the original string, and the second line logs the resulting array.

Harry Trump ;Fred Barney; Helen Rigby ; Bill Abel ;Chris Hand 
[ "Harry Trump", "Fred Barney", "Helen Rigby", "Bill Abel", "Chris Hand", "" ]

Returning a limited number of splits

In the following example, split() looks for spaces in a string and returns the first 3 splits that it finds.

const myString = 'Hello World. How are you doing?';
const splits = myString.split(' ', 3);

console.log(splits);

This script displays the following:

["Hello", "World.", "How"]

Splitting with a RegExp to include parts of the separator in the result

If separator is a regular expression that contains capturing parentheses (), matched results are included in the array.

const myString = 'Hello 1 word. Sentence number 2.';
const splits = myString.split(/(\d)/);

console.log(splits);

This script displays the following:

[ "Hello ", "1", " word. Sentence number ", "2", "." ]

Reversing a String using split()

This is not a robust way to reverse a string:

const str = 'asdfghjkl';
const strReverse = str.split('').reverse().join(''); // 'lkjhgfdsa'
// split() returns an array on which reverse() and join() can be applied

It doesn't work if the string contains grapheme clusters, even when using a unicode-aware split (use for example esrever instead).

const str = 'résumé';
const strReverse = str.split(/(?:)/u).reverse().join('');
// => "́emuśer"

Bonus: use === operator to test if the original string was a palindrome.

Specifications

Specification Status Comment
ECMAScript 3rd Edition (ECMA-262) Standard Initial definition. Implemented in JavaScript 1.1.
ECMAScript 5.1 (ECMA-262)
The definition of 'String.prototype.split' in that specification.
Standard
ECMAScript 2015 (6th Edition, ECMA-262)
The definition of 'String.prototype.split' in that specification.
Standard
ECMAScript Latest Draft (ECMA-262)
The definition of 'String.prototype.split' in that specification.
Draft

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
splitChrome Full support 1Edge Full support 12Firefox Full support 1IE Full support 4Opera Full support YesSafari Full support YesWebView Android Full support 1Chrome Android Full support 18Firefox Android Full support 4Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support 1.0nodejs Full support Yes

Legend

Full support  
Full support

See also