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codePointAt

Return a Unicode code point from a string at a specified position.

Installation

npm install @stdlib/string-code-point-at

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 codePointAt = require( '@stdlib/string-code-point-at' );

codePointAt( string, position[, backward] )

Returns a Unicode code point from a string at a specified position.

var out = codePointAt( 'last man standing', 4 );
// returns 32

The function supports providing a backward argument for performing backward iteration for low surrogates.

var out = codePointAt( '🌷', 1, true );
// returns 127799

The function supports providing a negative position.

var out = codePointAt( 'last man standing', -13 );
// returns 32

Notes

This function differs from String.prototype.codePointAt in the following ways:

• The function supports providing a negative position. If provided a negative position, the function determines the string position relative to the end of the string.
• The function supports providing a backward argument for performing backward iteration for low surrogates. String.prototype.codePointAt simply returns the low surrogate value if no UTF-16 surrogate pair begins at the specified position. If invoked with backward set to true, this function will return the code point after aggregating with the preceding high surrogate, if the specified position does not mark the start of a surrogate pair.
• The function raises an exception if provided a position which exceeds the bounds of the input string.

Examples

var codePointAt = require( '@stdlib/string-code-point-at' );

var v = codePointAt( 'last man standing', 4 );
// returns 32

v = codePointAt( 'presidential election', 8, true );
// returns 116

v = codePointAt( 'अनुच्छेद', 2 );
// returns 2369

v = codePointAt( '🌷', 1, true );
// returns 127799

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CLI

Installation

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

npm install -g @stdlib/string-code-point-at-cli

Usage

Usage: code-point-at [options] --pos=<index> [<string>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
  -b,    --backward            Backward iteration for low surrogates.
         --pos index           Position in string.

Examples

$ code-point-at --pos=2 अनुच्छेद
2369

To use as a standard stream,

$ echo -n 'अनुच्छेद' | code-point-at --pos=2
2369

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See Also

• @stdlib/string-from-code-point: create a string from a sequence of Unicode code points.

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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

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.