stdlib-js
<summary>
About stdlib...
</summary>
We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.
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lpad
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
Left pad a string.
bash
npm install @stdlib/string-left-pad
javascript
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.
javascript
var str = lpad( 'a', 5 );
// returns ' a'
By default, an input string is padded with a Unicode "space" character (U+0020). To pad with a different character or sequence of characters, provide a pad string.
javascript
var str = lpad( 'beep', 10, 'b' );
// returns 'bbbbbbbeep'
str = lpad( 'boop', 12, 'beep' );
// returns 'beepbeepboop'
len, but to have a length of at least len. To generate a padded string having a length equal to len
javascript
var str = lpad( 'boop', 10, 'beep' ); // => length 12
// returns 'beepbeepboop'
str = str.substring( str.length-10 ); // => length 10
// returns 'epbeepboop'
- This function differs from [String.prototype.padStart][mdn-string-padstart] in the following ways:
- The function is not guaranteed to return a string having a length exactly equal to len (as explained above).
- The function does not truncate pad (from the end) in order to ensure the returned string has length len.
To replicate [String.prototype.padStart][mdn-string-padstart] truncation behavior
javascript
var floorb = require( '@stdlib/math-base-special-floorb' );
function padStart( str, len, pad ) {
var n;
if ( len <= str.length ) {
return str;
}
n = floorb( len-str.length, 1, pad.length ) + str.length;
return pad.substring( 0, len-n ) + lpad( str, n, pad );
}
var str = padStart( 'boop', 10, 'beep' );
// returns 'bebeepboop'
javascript
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var lpad = require( '@stdlib/string-left-pad' );
var str = 'beep';
var i;
for ( i = 0; i < 100; i++ ) {
console.log( lpad( str, discreteUniform( str.length, str.length+10 ), 'b' ) );
}
@stdlib/string-left-pad-cli][@stdlib/string-left-pad-cli]: CLI package for use as a command-line utility.
- [@stdlib/string-pad][@stdlib/string/pad]: pad a string.
- [@stdlib/string-right-pad][@stdlib/string/right-pad]: right pad a string.
