Nunjucks limitTo filter. Creates a new array or string containing only a specified number of elements. The elements are taken from either the beginning or the end of the source array or string, as specified by the value and sign (positive or negative) of limit.

nunjucks-filter-limit-to.js

/**
 * @module limitTo
 *
 * Creates a new array or string containing only a specified number of elements.
 * The elements are taken from either the beginning or the end of the source array
 * or string, as specified by the value and sign (positive or negative) of limit.
 *
 * Same behavior as AngularJS limitTo filter: http://docs.angularjs.org/api/ng/filter/limitTo
 *
 * To use this filter in a template, first register it in the Nunjucks environment:
 *   env.addFilter('limitTo', limitTo);
 *
 * @example <caption>Limit to first 5 characters of string</caption>
 *   {{ "hello world" | limitTo(5) }}
 *   // outputs: hello
 *
 * @example <caption>Limit to last 5 characters of string</caption>
 *   {{ "hello world" | limitTo(-5) }}
 *   // outputs: world
 *
 * @example <caption>Limit to first 3 items in array</caption>
 *   {% set items = ["alpha","beta","charlie","delta","echo"] %}
 *   {% for item in items | limitTo(3) %} {{ loop.index }}.{{ item }} {% endfor %}
 *   // outputs: 1.alpha 2.beta  3.charlie
 *
 * @example <caption>Limit to last 3 items in array</caption>
 *   {% set items = ["alpha","beta","charlie","delta","echo"] %}
 *   {% for item in items | limitTo(-3) %} {{ loop.index }}.{{ item }} {% endfor %}
 *   // outputs: 1.charlie 2.delta 3.echo
 *
 * @param {String|Array} input  text or list of items to shorten
 * @param {Number} limit        either positive offset from start or negative offset from end
 */
function limitTo(input, limit){
	'use strict';
	if(typeof limit !== 'number'){
		return input;
	}
	if(typeof input === 'string'){
		if(limit >= 0){
			return input.substring(0, limit);
		} else {
			return input.substr(limit);
		}
	}
	if(Array.isArray(input)){
		limit = Math.min(limit, input.length);
		if(limit >= 0){
			return input.splice(0, limit);
		} else {
			return input.splice(input.length + limit, input.length);
		}
	}
	return input;
}

module.exports = limitTo;