All files main.js

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/**
* @license Apache-2.0
*
* Copyright (c) 2026 The Stdlib Authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*    http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
 
'use strict';
 
// MODULES //
 
var numCodePoints = require( '@stdlib/string/num-code-points' );
var nextCodePointIndex = require( '@stdlib/string/next-code-point-index' );
 
 
// MAIN //
 
/**
* Truncates a string to a specified length in code points.
*
* @param {string} str - input string
* @param {NonNegativeInteger} len - output string length (including ending)
* @param {string} ending - custom ending
* @returns {string} truncated string
*
* @example
* var out = truncate( 'beep boop', 7, '...' );
* // returns 'beep...'
*
* @example
* var out = truncate( 'beep boop', 5, '>>>' );
* // returns 'be>>>'
*
* @example
* var out = truncate( 'beep boop', 10, '...' );
* // returns 'beep boop'
*
* @example
* var out = truncate( 'beep boop', 0, '...' );
* // returns ''
*
* @example
* var out = truncate( 'beep boop', 2, '...' );
* // returns '..'
*
* @example
* var out = truncate( '🐺 Wolf Brothers 🐺', 7, '...' );
* // returns '🐺 Wo...'
*/
function truncate( str, len, ending ) {
	var endingLength;
	var nVisual;
	var idx;
 
	endingLength = numCodePoints( ending );
	if ( len >= numCodePoints( str ) ) {
		return str;
	}
	if ( len - endingLength <= 0 ) {
		idx = 0;
		nVisual = 0;
		while ( nVisual < len ) {
			idx = nextCodePointIndex( ending, idx );
			if ( idx === -1 ) {
				idx = ending.length;
				break;
			}
			nVisual += 1;
		}
		return ending.substring( 0, idx );
	}
	idx = 0;
	nVisual = 0;
	while ( nVisual < len - endingLength ) {
		idx = nextCodePointIndex( str, idx );
		if ( idx === -1 ) {
			idx = str.length;
			break;
		}
		nVisual += 1;
	}
	return str.substring( 0, idx ) + ending;
}
 
 
// EXPORTS //
 
module.exports = truncate;