program.js

var util = require('util');

function countWords(inputWords) {
    return inputWords.reduce(function (prev, cur) {
        if (!util.isObject(prev)) {
            var obj = {};
            obj[prev] = 1;
            obj[cur] = 1;
            return obj;
        }
        if (!prev[cur]) {
            prev[cur] = 0;
        }
        ++prev[cur];

        return prev;
    });
}

module.exports = countWords;