Create character groups from a source string

GroupCharacters.js

// GroupCharacters('abc', 2)
// ["ab", "c"]
function GroupCharacters(sourceString, groupLength)
{
    return sourceString.split('').reduce(function(groupedStrings, currentCharacter) {
        var lastGrouping = groupedStrings.pop();

        if(lastGrouping.length < groupLength)
        {
            lastGrouping += currentCharacter;
            groupedStrings.push(lastGrouping);
        }
        else
        {
            groupedStrings.push(lastGrouping);
            groupedStrings.push(String(currentCharacter));
        }

        return groupedStrings;
    }, ['']);
}