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Return the part of a string before a specified substring.

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stdlib-js/string-substring-before

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substringBefore

NPM version Build Status Coverage Status

Return the part of a string before a specified substring.

Installation

npm install @stdlib/string-substring-before

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 substringBefore = require( '@stdlib/string-substring-before' );

substringBefore( str, search )

Returns the part of a string before a specified substring.

var str = 'beep boop';
var out = substringBefore( str, ' ' );
// returns 'beep'

out = substringBefore( str, 'o' );
// returns 'beep b'

Notes

  • If a substring is not present in a provided string, the function returns the input string.
  • If provided an empty substring, the function returns an empty string.

Examples

var substringBefore = require( '@stdlib/string-substring-before' );

var out = substringBefore( 'beep boop', 'p' );
// returns 'bee'

out = substringBefore( 'Hello World!', 'xyz' );
// returns 'Hello World!'

out = substringBefore( 'Hello World!', '' );
// returns ''

out = substringBefore( '', 'xyz' );
// returns ''

CLI

Installation

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

npm install -g @stdlib/string-substring-before-cli

Usage

Usage: substring-before [options] --search=<string> [<string>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --search string       Search string.
         --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 $'foo\nbar\nbaz' | substring-before --search a --split /\r?\n/
    
    # Escaped...
    $ echo -n $'foo\nbar\nbaz' | substring-before --search a --split /\\r?\\n/
  • The implementation ignores trailing delimiters.

Examples

$ substring-before abcdefg --search d
abc

To use as a standard stream,

$ echo -n $'beep\nboop' | substring-before --search p
bee
boo

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' | substring-before --search p --split '\t'
bee
boo

See Also


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.

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License

See LICENSE.

Copyright

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