chaining and indentation

1.js

var users = records.map(function(record) {
                        return record.username;
                    })
                   .filter(function(username) { return !!username })
                   .map(function(username) {
                        return username.toLowerCase();
                    });

2.js

var users = records.map(function(record) {
                       return record.username;
                   })
                   .filter(function(username) { return !!username })
                   .map(function(username) {
                       return username.toLowerCase();
                   });

3.js

var users = records.map(function(record) {
                            return record.username;
                        })
                   .filter(function(username) { return !!username })
                   .map(function(username) {
                            return username.toLowerCase();
                        });

4.js

var users = records.map(function(record) {
    return record.username;
})
                   .filter(function(username) { return !!username })
                   .map(function(username) {
    return username.toLowerCase();
});