html5生成柱状图（条形图）

<html>
<canvas id="a_canvas" width="1000" height="700"></canvas>
<script>
    (function (){

        window.addEventListener("load", function(){

          var data = [1000,1300,2000,3000,2000,2000,1000,1500,2000,5000,1000,1000];
		  var xinforma = [\'1月\',\'2月\',\'3月\',\'4月\',\'5月\',\'6月\',\'7月\',\'8月\',\'9月\',\'10月\',\'11月\',\'12月\'];

          // 获取上下文
          var a_canvas = document.getElementById(\'a_canvas\');
          var context = a_canvas.getContext("2d");


          // 绘制背景
          var gradient = context.createLinearGradient(0,0,0,300);


         // gradient.addColorStop(0,"#e0e0e0");
          //gradient.addColorStop(1,"#ffffff");


          context.fillStyle = gradient;

          context.fillRect(0,0,a_canvas.width,a_canvas.height);

          var realheight = a_canvas.height-15;
		  var realwidth = a_canvas.width-40;
          // 描绘边框
          var grid_cols = data.length + 1;
          var grid_rows = 4;
          var cell_height = realheight / grid_rows;
          var cell_width = realwidth / grid_cols;
          context.lineWidth = 1;
          context.strokeStyle = "#a0a0a0";

          // 结束边框描绘
          context.beginPath();
          // 准备画横线
          /*for(var row = 1; row <= grid_rows; row++){
            var y = row * cell_height;
            context.moveTo(0,y);
            context.lineTo(a_canvas.width, y);
          }*/
		 
		  	//划横线
		  	context.moveTo(0,realheight);
			context.lineTo(realwidth,realheight);
			   
			
			//画竖线
		  context.moveTo(0,20);
           context.lineTo(0,realheight);
          context.lineWidth = 1;
          context.strokeStyle = "black";
          context.stroke();
		     

          var max_v =0;
         
          for(var i = 0; i<data.length; i++){
            if (data[i] > max_v) { max_v =data[i]};
          }
          max_v = max_v * 1.1;
          // 将数据换算为坐标
          var points = [];
          for( var i=0; i < data.length; i++){
            var v= data[i];
            var px = cell_width *　(i +1);
            var py = realheight - realheight*(v / max_v);
			//alert(py);
            points.push({"x":px,"y":py});
          }

          //绘制坐标图形
          for(var i in points){
            var p = points[i];
            context.beginPath();
			context.fillStyle="green";
			context.fillRect(p.x,p.y,15,realheight-p.y);
			
            context.fill();
          }
		  //添加文字
		  for(var i in points)
		  {  var p = points[i];
            context.beginPath();
			context.fillStyle="black";
		    context.fillText(data[i], p.x + 1, p.y - 15);
			 context.fillText(xinforma[i],p.x + 1,realheight+12);
             context.fillText(\'月份\',realwidth,realheight+12);
			 context.fillText(\'资金量\',0,10);
			  }
        },false);
      })();
	  
</script>
</html>
html5生成柱状图（条形图）详细代码
运行结果：