@stdlib/string-left-pad

Left Pad

Left pad a string.

Installation

npm install @stdlib/string-left-pad

Usage

var lpad = require( '@stdlib/string-left-pad' );

lpad( str, len[, pad] )

Left pads a string such that the padded string has a length of at least len.

var str = lpad( 'a', 5 );
// returns '    a'

By default, an input string is padded with spaces. To pad with a different character or sequence of characters, provide a pad string.

var str = lpad( 'beep', 10, 'b' );
// returns 'bbbbbbbeep'

str = lpad( 'boop', 12, 'beep' );
// returns 'beepbeepboop'

Notes

• An output string is not guaranteed to have a length of exactly len, but to have a length of at least len. To generate a padded string having a length equal to len

  var str = lpad( 'boop', 10, 'beep' ); // => length 12
  // returns 'beepbeepboop'
  
  str = str.substring( str.length-10 ); // => length 10
  // returns 'epbeepboop'

Examples

var round = require( '@stdlib/math-base-special-round' );
var randu = require( '@stdlib/random-base-randu' );
var lpad = require( '@stdlib/string-left-pad' );

var str = 'beep';
var n;
var i;

for ( i = 0; i < 100; i++ ) {
    n = round( randu()*10 ) + str.length;
    console.log( lpad( str, n, 'b' ) );
}

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CLI

Installation

To use the module as a general utility, install the module globally

npm install -g @stdlib/string-left-pad

Usage

Usage: lpad [options] [<string>] --len=<length>

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --len length          Minimum string length.
         --pad str             String used to pad. Default: ' '.
         --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 $'beep\nboop' | lpad -len 8 --split /\r?\n/
  
  # Escaped...
  $ echo -n $'beep\nboop' | lpad -len 8 --split /\\r?\\n/

• The implementation ignores trailing delimiters.

Examples

$ lpad beep --len 10 --pad b
bbbbbbbeep

To use as a standard stream,

$ echo -n 'beep' | lpad --len 8
    beep

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 'boop\tbeep' |  lpad --len 8 --split '\t'
    boop
    beep

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See Also

• @stdlib/string/pad: pad a string.
• @stdlib/string/right-pad: right pad a string.

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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 © 2016-2022. The Stdlib Authors.