JS: Angular Url Friendly Filter. Can be used to create url friendly permalinks from blog titles. Port of url_title in Codeigniter.

UrlFriendly.Filter.js

define(['angular'], function(angular){

	'use strict';

	angular.module('Filters')
		.filter('UrlFriendly', [
			function(){
				return function(text, separator, lowercase){

					var output,
						q_separator,
						translation = {},
						tags,
						commentsAndPhpTags,
						key,
						replacement,
						leadingTrailingSeparators;

					//default separator
					if(!separator){
						separator = '_';
					}

					//escape all possible regex characters in the separator to create a "searchable" separator
					//equivalent to preg_quote in php
					q_separator = (separator + '').replace(new RegExp('[.\\\\+*?\\[\\^\\]$(){}=!<>|:\\-]', 'g'), '\\$&');

					//regex to replacement object
					translation['&.+?;'] = ''; //remove html entities
					translation['[^a-z0-9 _-]'] = ''; //remove anything other than alphanumeric, spaces, underscores and dashes
					translation['\\s+'] = separator; //change whitespace to separator (regexp requires extra escaping of backslashes)
					translation['(' + q_separator + ')+'] = separator; //change escaped separator to separator

					//strip html tags from the title
					tags = /<\/?([a-z][a-z0-9]*)\b[^>]*>/gi;
					commentsAndPhpTags = /<!--[\s\S]*?-->|<\?(?:php)?[\s\S]*?\?>/gi;
					output = text.replace(commentsAndPhpTags, '').replace(tags, '');

					//change!
					for(key in translation){
						replacement = translation[key];
						key = new RegExp(key, 'ig');
						output = output.replace(key, replacement);
					}

					//lowercase the title if necessary
					if(lowercase){
						output = output.toLowerCase();
					}

					//trim leading and trailing separators in case there was multiple spaces
					leadingTrailingSeparators = new RegExp('^' + q_separator + '+|' + q_separator + '+$');
					output = output.replace(leadingTrailingSeparators, '');

					//es5 trim out whitespace, make sure to polyfill this for older browsers
					output = output.trim();

					return output;

				};
			}
		]);

});