AutocompleteBuilder.js

/* PHP similar_text JavaScript implementation
see: http://phpjs.org/functions/similar_text/ */
function similar_text(first, second, percent)
{
    //  discuss at: http://phpjs.org/functions/similar_text/
    // original by: Rafał Kukawski (http://blog.kukawski.pl)
    // bugfixed by: Chris McMacken
    // bugfixed by: Jarkko Rantavuori original by findings in stackoverflow (http://stackoverflow.com/questions/14136349/how-does-similar-text-work)
    // improved by: Markus Padourek (taken from http://www.kevinhq.com/2012/06/php-similartext-function-in-javascript_16.html)
    //   example 1: similar_text('Hello World!', 'Hello phpjs!');
    //   returns 1: 7
    //   example 2: similar_text('Hello World!', null);
    //   returns 2: 0

    if(first === null || second === null || typeof first === 'undefined' || typeof second === 'undefined')
    {
        return 0;
    }

    first += '';
    second += '';

    var pos1 = 0,
        pos2 = 0,
        max = 0,
        firstLength = first.length,
        secondLength = second.length,
        p, q, l, sum;

    max = 0;

    for(p = 0; p < firstLength; p++)
    {
        for(q = 0; q < secondLength; q++)
        {
            for(l = 0;
                (p + l < firstLength) && (q + l < secondLength) && (first.charAt(p + l) === second.charAt(q + l)); l++)
            ;
            if(l > max)
            {
                max = l;
                pos1 = p;
                pos2 = q;
            }
        }
    }

    sum = max;

    if(sum)
    {
        if(pos1 && pos2)
        {
            sum += this.similar_text(first.substr(0, pos1), second.substr(0, pos2));
        }

        if((pos1 + max < firstLength) && (pos2 + max < secondLength))
        {
            sum += this.similar_text(first.substr(pos1 + max, firstLength - pos1 - max), second.substr(pos2 + max,
                secondLength - pos2 - max));
        }
    }

    if(!percent)
    {
        return sum;
    }
    else
    {
        return (sum * 200) / (firstLength + secondLength);
    }
}

/*
Usage:
var library = [
    {
         'title': 'OpenGL Programming Guide'
         ...
    }
    ...
];
var books = new AutocompleteBuilder(library, 'title');
books.search('guide');
*/

function AutocompleteBuilder(array, key)
{
	this.array = array;
	this.key = key;
}

AutocompleteBuilder.prototype.search = function(str)
{
	str = str.toLowerCase();
	for(var i = 0; i < this.array.length; i++)
		this.array[i].similarity = similar_text(str, this.array[i][this.key].toLowerCase(), true);
	
	return this.array.sort(function(a, b)
		{ return b.similarity - a.similarity; });
}