JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://underscorejs.org/underscore.js"></script>
<div id="contents" />

CoffeeScript

# Define a function that takes:
# obj - an object to iterate over
# consSize - the number of consecutive items to get 
# iterator - a function we'll with each subset of items
# context - becomes 'this' when in the iterator function
conser = (obj, consSize, iterator, context) ->
  for i in [0..obj.length-consSize]
    stop = i + consSize
    stop = obj.length if stop > obj.length
    slice = obj[i...stop]
    iterator.call(context, slice, i, obj)

_.mixin({"eachCons": conser})

a = [1,2,3,4,5,6]
printer = (s) -> $("#contents").append("<p>#{s}</p>")
_.eachCons(a, 3, printer )