JSFiddle - React, Tailwind, and code Playground

by Eric Howe

HTML

<script src="http://documentcloud.github.com/underscore/underscore-min.js"></script>

JavaScript

var words = [
    "apple",
    "apple",
    "pear",
    "pear",
    "kiwi",
    "peach"
];

function collect_dups(a, n, word) {
    if(n > 1)
        a.push(word);
    return a;
}
var dups = _(words).chain()
                   .countBy()
                   .reduce(collect_dups, [])
                   .value();
console.log(dups);