Chroma JS

HTML

<script src="//gka.github.io/chroma.js/vendor/chroma-js/chroma.min.js"></script>
<script src="//d3js.org/d3.v3.min.js"></script>
<link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
<div class="container-fluid" id='main'>
    <div class="row">
        <div class="col-md-12">
           <div id="palette"></div> 
        </div>
    </div>
</div>

CSS

#main{margin-top: 40px;}

JavaScript

var f  = chroma.scale(['blue', 'red']);
console.log(f(0.5));