JavaScript String API Reference

`String`

11 methods

Immutable sequence of UTF-16 code units.

str.split(separator?, limit?)

Split the string into an array of substrings.

Parameters

Name	Type	Description
separator	string \| RegExp	Delimiter (string or regex).
limit	number	Maximum number of substrings.

Returns

string[]

Example

javascript

'a,b,c'.split(',')        // ['a', 'b', 'c']
'hello'.split('')         // ['h','e','l','l','o']
'a-b-c'.split('-', 2)     // ['a', 'b']

str.replace(pattern, replacement)

Return a new string with the first match of pattern replaced. Use replaceAll for all matches.

Parameters

Name	Type	Description
pattern	string \| RegExp	Pattern to match.
replacement	string \| Function	Replacement string or function.

Returns

string

Example

javascript

'hello world'.replace('world', 'JS')  // 'hello JS'
'a-b-c'.replace('-', '_')              // 'a_b-c'
'a-b-c'.replace(/-/g, '_')             // 'a_b_c'

str.match(regexp)

Return the result of matching a string against a regular expression.

Parameters

Name	Type	Description
regexp	RegExp	Regular expression (string is coerced).

Returns

Array | null

Example

javascript

'2024-01-15'.match(/(\d{4})-(\d{2})-(\d{2})/)
// ['2024-01-15', '2024', '01', '15']
'abc'.match(/\d/)  // null

str.trim()

Return a new string with whitespace removed from both ends.

Returns

string

Example

javascript

'  hi  '.trim()  // 'hi'
'\n hello\n'.trim()  // 'hello'

str.padStart(targetLength, padString?)

Pad the string from the start with padString until it reaches targetLength.

Parameters

Name	Type	Description
targetLength	number	Final length.
padString	string	Padding string (default space).

Returns

string

Example

javascript

'5'.padStart(3, '0')     // '005'
'abc'.padStart(6, '*')   // '***abc'

str.padEnd(targetLength, padString?)

Pad the string from the end with padString until it reaches targetLength.

Parameters

Name	Type	Description
targetLength	number	Final length.
padString	string	Padding string (default space).

Returns

string

Example

javascript

'5'.padEnd(3, '0')     // '500'
'abc'.padEnd(6, '*')   // 'abc***'

str.includes(searchString, position?)

Return true if searchString is found within the string.

Parameters

Name	Type	Description
searchString	string	Substring to search for.
position	number	Start position (default 0).

Returns

boolean

Example

javascript

'hello world'.includes('world')  // true
'hello'.includes('a')             // false

str.startsWith(searchString, position?)

Return true if the string starts with searchString.

Parameters

Name	Type	Description
searchString	string	Prefix to check.
position	number	Start position (default 0).

Returns

boolean

Example

javascript

'hello'.startsWith('he')  // true
'hello'.startsWith('el', 1)  // true

str.endsWith(searchString, length?)

Return true if the string ends with searchString.

Parameters

Name	Type	Description
searchString	string	Suffix to check.
length	number	Consider the string as length characters long.

Returns

boolean

Example

javascript

'hello'.endsWith('lo')  // true
'hello'.endsWith('ell', 4)  // true

str.repeat(count)

Return a new string consisting of count copies of the original.

Parameters

Name	Type	Description
count	number	Number of copies.

Returns

string

Example

javascript

'ab'.repeat(3)  // 'ababab'
'-'.repeat(5)   // '-----'

str.substring(start, end?)

Return the substring from start to end (end excluded).

Parameters

Name	Type	Description
start	number	Start index.
end	number	End index (default length).

Returns

string

Example

javascript

'hello'.substring(1, 3)  // 'el'
'hello'.substring(2)      // 'llo'

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