[D3] 4. d3.max

how to use d3.max to normalize your dataset visually within the specific bounds of a variable domain.

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <script src="../bower_components/underscore/underscore-min.js"></script>
    <script src="../ventor/d3.min.js"></script>
    <style type="text/css">

        body
        {
            padding-top: 50px;
            padding-left: 100px;

        }

        #chartArea {
            width: 400px;
            height: 300px;
            background-color: #CCC;
        }

        .bar
        {
            display: inline-block;
            width: 20px;
            height: 75px; /* Gets overriden by D3-assigned height below */
            margin-right: 2px;
            fill: teal; /* SVG doesn't have background prop, use fill instead*/
            z-index:99;
        }

    </style>
</head>
<body>
<section id="chartArea"></section>
<script>
    var dataset = _.map(_.range(15), function(num) {
        return Math.random() * 50;
    }), //reandom generate 15 data from 1 to 50
            w = 400, h = 300;
    var svg = d3.select('#chartArea').append('svg')
            .attr('width', w)
            .attr('height', h); //svg deosn't need 'px'

    var yScale = d3.scale.linear()
            .domain([0, d3.max(dataset) * 1.1]) //d3.max(dataset), set the max val of database
            .range([0, h]);

    svg.selectAll('div')
            .data(dataset)
            .enter()
            .append('rect')// svg doesn't have div, use rect instead
            .attr('class', "bar")
            .attr('width', 20)
            .attr('x', function(each_data, index){
                return index*22;
            })
            .attr('y', function(each_data){
                return h-yScale(each_data);
            })
            .attr('height', function(each_data, i){
                return yScale(each_data);
            });
</script>

<!--
    1. svg should use 'fill' prop instead 'background-color'
    2. svg width & height no need 'px'
    3. attr(function(data_val, index){})
    4. create svg, d3.select('selector').append('svg').attr('width', xxx).attr('height', xx)
    5. svg should use 'rect' instead of 'div'
    -->
</body>
</html>