JS Bin// source https://jsbin.com/qezako

reverseWords.js

'use strict';

function reverseWords(str) {

    var reversedString = [],
        wordLen = 0;

    for (var i = str.length - 1; i >= 0; i--) {

        if (str[i] == ' ' || i === 0) {

            var word = str.substr(i, wordLen + 1).trim();
            reversedString.push(word);
            wordLen = 0;
        } else {
            wordLen++;
        }
    }

    return reversedString.join(' ');
}

console.log(reverseWords('The real voyage of discovery consists not in seeking new lands but seeing with new eyes.'));