String weaver

weaver.js

'use strict';

module.exports = function stringWeaver(stringArray, sortByLength) {

    sortByLength = sortByLength || true;

    var result = [],
        index = 0,
        lastIndex = 0;

    if (sortByLength) {
        stringArray.sort(function (a, b) { return a.length - b.length; });
    }

    stringArray.forEach(function(string) {

        string = string.split('');
        string.forEach(function(char) {
            if (index > 0) {
                result.splice(index, 0, char);
                index += (lastIndex + 1);
            } else {
                result.push(char);
            }
        });

        lastIndex += 1;
        index = lastIndex;
    });

    return result.join('');
};