About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

first

Return the first character(s) of a string.

Installation

npm install @stdlib/string-first

Alternatively,

To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
If you are using Deno, visit the deno branch (see README for usage intructions).
For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).
To use as a general utility for the command line, install the corresponding CLI package globally.

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var first = require( '@stdlib/string-first' );

first( str[, n][, options] )

Returns the first character(s) of a string.

var out = first( 'last man standing' );
// returns 'l'

out = first( 'Hidden Treasures' );
// returns 'H'

The function supports the following options:

mode: type of characters to return. Must be one of the following:
- 'grapheme': grapheme clusters. Appropriate for strings containing visual characters which can span multiple Unicode code points (e.g., emoji).
- 'code_point': Unicode code points. Appropriate for strings containing visual characters which are comprised of more than one Unicode code unit (e.g., ideographic symbols and punctuation and mathematical alphanumerics).
- 'code_unit': UTF-16 code units. Appropriate for strings containing visual characters drawn from the basic multilingual plane (BMP) (e.g., common characters, such as those from the Latin, Greek, and Cyrillic alphabets).
Default: 'grapheme'.

By default, the function returns the first character. To return the first n characters, provide a second argument specifying the number of characters to return.

var out = first( 'foo bar', 5 );
// returns 'foo b'

out = first( 'foo bar', 10 );
// returns 'foo bar'

Notes

By default, the function assumes the general case in which an input string may contain an arbitrary number of grapheme clusters. This assumption comes with a performance cost. Accordingly, if an input string is known to only contain visual characters of a particular type (e.g., only alphanumeric), one can achieve better performance by specifying the appropriate mode option.

Examples

var first = require( '@stdlib/string-first' );

var str = first( 'last man standing' );
// returns 'l'

str = first( 'presidential election' );
// returns 'p'

str = first( 'javaScript' );
// returns 'j'

str = first( 'Hidden Treasures' );
// returns 'H'

str = first( 'The Last of the Mohicans', 5 );
// returns 'The L'

str = first( '🐶🐮🐷🐰🐸', 2 );
// returns '🐶🐮'

str = first( '🐶🐮🐷🐰🐸', 10 );
// returns '🐶🐮🐷🐰🐸'

CLI

Installation

To use as a general utility, install the CLI package globally

npm install -g @stdlib/string-first-cli

Usage

Usage: first [options] [<string>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --n num               Number of characters to return. Default: 1.
         --split sep           Delimiter for stdin data. Default: '/\\r?\\n/'.
         --mode mode           Type of character to return. Default: 'grapheme'.

Notes

If the split separator is a regular expression, ensure that the split option is either properly escaped or enclosed in quotes.

# Not escaped...
$ echo -n $'beep\nboop' | first --split /\r?\n/

# Escaped...
$ echo -n $'beep\nboop' | first --split /\\r?\\n/

The implementation ignores trailing delimiters.

Examples

$ first beep
b

To use as a standard stream,

$ echo -n 'beep\nboop' | first --n=2
be
bo

By default, when used as a standard stream, the implementation assumes newline-delimited data. To specify an alternative delimiter, set the split option.

$ echo -n 'beep\tboop' | first --split '\t'
b
b

See Also

@stdlib/string-remove-first: remove the first character(s) of a string.
@stdlib/string-last: return the last character(s) of a string.

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2025. The Stdlib Authors.

Uh oh!