Return the first character(s) of a string.

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

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'

• 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.

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 '🐶🐮🐷🐰🐸'

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'.

• 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.

$ 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

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