Hello, please or register

Javascript Sort Algorithm

Almost a year ago (when the latest piece of tech was the abacus and debugging was done with a citrusy-vinegar mix) i was given the coding challenge for an interview with a Spanish social networking site (who shall remain nameless). One of the questions was quite a good exercise for the Javascript Array.sort function, which i want to keep+share with you today.

¿Here are a bunch of tickets, sort them with javascript - por favor?

From Stockholm, take flight SK22 to New York JFK. Gate 22, seat 7B. Baggage will we automatically transferred from your last leg.
Take train 78A from Madrid to Barcelona. Sit in seat 45B.
From Gerona Airport, take flight SK455 to Stockholm. Gate 45B, seat 3A. Baggage drop at ticket counter 344.
Take the airport bus from Barcelona to Gerona Airport. No seat assignment.

Code

var ordertickets = {

	// Stops is an unordered list of stops which need to be sorted... this dwindles as the method is run
	stops : [],
	// the journey contains the ordered list of stops.
	journey : [],

	// Run at start
	// @param string Element Attr(id) Source list
	// @param string Element Attr(id) Target list
	init : function(id, idorderedlist){
		this.journey = [];
		// Get the children from the list who's 
		var listops = document.getElementById(id).children;
		var points = {'to':[],'from':[]};
		// get the stops from the HTML list
		for( var i=0;i<listops.length;i++){
			this.stops.push( listops[i].innerHTML );
			// get the first and last positions. These are only mentioned once.
			var res;
			if( res = listops[i].innerHTML.match(/[fF]rom\s*([A-Z]\w+).*?[tT]o\s*([A-Z]\w+)/) ){
				// add name to array
				points['from'].push(res[1]);
				points['to'].push(res[2]);
			};
		}
		// Get the unique points
		points = this.uniquepoints(points);
		
		// Sort and order the list
		this.sort(points);

		// clear ordered list
		document.getElementById(idorderedlist).innerHTML = '';

		// create the ordered list and append it
		this.createorderedlist(idorderedlist);
	},
	
	// Sort the journey
	// @param object {'from':string, 'to':string}
	
	sort : function(points){
	
		this.journey = this.stops.sort(function(a,b){
			// get from
			var regf = /[fF]rom\s+([A-Z]\w+)/,
				regt = /[tT]o\s+([A-Z]\w+)/,
				a_from = a.match(regf)[1],
				a_to = a.match(regt)[1],
				b_from = b.match(regf)[1],
				b_to = b.match(regt)[1];
	
			if( a_to === b_from )
				r = -1;
			else if( a_from === b_to )
				r = 1;
			else if( a_from === points.from )
				r = -1;
			else if( a_to === points.to )
				r = 1;
			
			//console.log([a_from, a_to, b_from, b_to, r]);
	
			return r;
		});
	},
	
	
	// From two arrays get the array_diff of the names and for each array return the single unique value.
	// @param object {'from':array, 'to':array}
	
	uniquepoints : function(points){
		// filter arrays to find the unique starting and ending points.
		for(var i=0; i<points['from'].length;i++ )
			for(var j=0; j<points['to'].length;j++ )
				if( points['to'][j] === points['from'][i] ){
					points['to'].splice(j,1);
					points['from'].splice(i,1);
					i--;
					j--;
				}

		return {'to':points['to'][0], 'from':points['from'][0]};
	},
	
	// create an ordered list from the values given
	// @param string Element attr(id=)
	createorderedlist : function(id){
		// populate the ordered list
		for( x in this.journey ){
			document.getElementById(id).innerHTML += '<li>'+this.journey[x]+'</li>';
		}
	}
}

It worked... but they gave the job to someone else, Estoy muy triste !