GitHub repository sorting

repositories.js

/*
repositories is a list of repository objects, in the form of
[
{name: "repo A", description: "my first repository!"},
{name: "repo B", description: "my second repository!"}
]
This is the same form as returned by the GitHub API: https://api.github.com/users/panchr/repos

query is just the search query as a string, such as "repo python my first"
*/

function rankRepositories(repositories, query) {
	// Rank the repositories based on query
	var queryWords = query.split(" ").filter(function (string) {
		return string.length > 1;
		});
	var re = new RegExp(queryWords.join("|"), "gi");

	var sortedRepositories = repositories
		.filter(function (elem) {
			return re.test(elem.name) || re.test(elem.description);
			})
		.sort(function (a, b) {
			var rankA = repositoryRank(a, re);
			var rankB = repositoryRank(b, re);
			if (rankA < rankB) return 1;
			else if (rankA > rankB) return -1;
			else return 0;
			});
	return sortedRepositories;
	}

function repositoryRank(repo, re) {
	// Returns a repository's rank
	return 5 * regexSimilarity(re, repo.name) + regexSimilarity(re, repo.description);
	}

function regexSimilarity(re, string) {
	// Returns the regex similarity for a string
	var matches = string.match(re);
	return (matches ? matches.length: 0) / string.length;
	}