D3——根据数据画图

为DOM元素添加class

.attr("class", "bar")  //为元素添加class属性,<div class="bar"></div>


.classed("bar", true)   //添加class "bar"
.classed("bar", false)  //删除class "bar"

Drawing Bars:

var dataset = [ 5, 10, 15, 20, 25 ];

d3.select("body").selectAll("div")
    .data(dataset)
    .enter()
    .append("div")
    .attr("class", "bar");


//css
div.bar {
    display: inline-block;
     20px;
    height: 75px;   /* We'll override height later */
    background-color: teal;
}

Setting Styles

.style("height", function(d) {
    return d + "px";
});

优化一下

.style("height", function(d) {
    var barHeight = d * 5;  //Scale up by factor of 5
    return barHeight + "px";
});  

//并设margin-right:2px;