time-to-botec/squiggle/node_modules/@stdlib/string/starts-with

startsWith

Test if a string starts with the characters of another string.

Usage

var startsWith = require( '@stdlib/string/starts-with' );

startsWith( str, search[, position] )

Tests if a string starts with the characters of another string.

var str = 'To be, or not to be, that is the question.';

var bool = startsWith( str, 'To be' );
// returns true

bool = startsWith( str, 'to be' );
// returns false

By default, the function searches from the beginning of the input string. To search from a different character index, provide a position value (zero-based). If provided a negative position, the start index is determined relative to the string end (pos = str.length + position).

var str = 'Remember the story I used to tell you when you were a boy?';

var bool = startsWith( str, 'the story' );
// returns false

bool = startsWith( str, 'the story', 9 );
// returns true

bool = startsWith( str, 'you', -15 );
// returns true

If provided an empty search string, the function always returns true.

var str = 'beep boop';

var bool = startsWith( str, '' );
// returns true

Examples

var startsWith = require( '@stdlib/string/starts-with' );

var bool;
var str;

str = 'Fair is foul, and foul is fair, hover through fog and filthy air';

bool = startsWith( str, 'Fair' );
// returns true

bool = startsWith( str, 'fair' );
// returns false

bool = startsWith( str, 'foul', 8 );
// returns true

bool = startsWith( str, 'filthy', -10 );
// returns true

---

CLI

Usage

Usage: starts-with [options] --search=<string> [<string>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --search string       Search string.
         --pos int             Search position.
         --split sep           Delimiter for stdin data. Default: '/\\r?\\n/'.

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 $'Hello, World!\nBeep Boop Baz' | starts-with --search=Beep --split /\r?\n/
  
  # Escaped...
  $ echo -n $'Hello, World!\nBeep Boop Baz' | starts-with --search=Beep --split /\\r?\\n/
  

• The implementation ignores trailing delimiters.

Examples

$ starts-with --search=be beep
true

To use as a standard stream,

$ echo -n 'boop' | starts-with --search=bo
true

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 'Hello, World!\tBeep Boop' | starts-with --search=Beep --split '\t'
false
true

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See Also

• @stdlib/string/ends-with: test if a string ends with the characters of another string.