gistfile1.txt

function reduce(arr, fn, initial) {

            //there's no more elements in the array, we return I get that
            if (arr.length === 0) {
                    return initial;
            } // base case, does not recurse

            // we are calling the actual function here with the first element in the array
            //I don't get what initial is ??

            initial = fn(initial, arr[0]);                      // sets init-OP-first result as new init

            //calling slice chops the head and passes the rest to reduce again.
            return reduce(arr.slice(1), fn, initial);
    }

    function sum(prev,next,index,arr) {
            return prev + next;
    }

    function countWords(countMap, word)  {
        countMap[word] = ++countMap[word] || 1 ;// increment or initialize to 1
        console.log(countMap[word]);
        return countMap;
     }

        var arr = [1,2,3,4];
        //sum the numbers in the array
        var total = reduce(arr,sum,0);
        console.log("total="+total);

        //count the number of words in a array
        var arr1 =  [ 'quis', 'velit', 'voluptate', 'nostrud', 'aute', 'ea', 'nostrud', 'occaecat', 'tempor', 'eu', 'ut', 'occaecat', 'labore', 'occaecat', 'aliqua', 'culpa', 'incididunt', 'ex' ];
        var tempArr = reduce(arr1,countWords,{});
        console.log("tempArr="+JSON.stringify(tempArr) );