SVG-矩形数据图

  <g  stroke="#545454" stroke-width="3">
    <line x1="100" y1="100" x2="100" y2="900"></line>
    <line x1="100" y1="900" x2="900" y2="900"></line>
    <polyline points="90,120 100,100 110,120" fill-opacity="0"></polyline>
    <polyline points="880,890 900,900 880,910" fill-opacity="0"></polyline>
  </g>

 function rc(min,max){
    var r=Math.round(Math.random()*(max-min));
    var g=Math.round(Math.random()*(max-min));
    var b=Math.round(Math.random()*(max-min));
    return "rgb("+r+","+g+","+b+")";
  }

  var xhr=new XMLHttpRequest();
  xhr.onreadystatechange=function(){
    if (xhr.readyState=="4"&&xhr.status=="200"){
      var data=eval("("+xhr.responseText+")");
      doResponse(data);
    }
  }
  xhr.open("GET","../res/curriculum",true);
  xhr.send(null);

var w=1000;
var h=1000;
  function doResponse(data){
//    设置矩形宽度
    var rectW=(w-200)/(data.length*2);
//    Y坐标轴据左边距离
    var baseLineL=100;
//    X坐标轴距顶部距离
    var baselineT=h-100;
//    创建文档碎片
    var trg=document.createDocumentFragment();
    for(var i=0;i<data.length;i++) {
//     获取随机颜色
      var r = rc(0, 255);
//      创建线性渐变,顺便创建文本-->
      var html = `<defs>
      <linearGradient id="g${i}" x1="0" y1="0" x2="0" y2="100%">
      <stop offset="0" stop-color="${r}"></stop>
      <stop offset="1" stop-color="#ffffff" stop-opacity="0"></stop>
      </linearGradient>
      </defs>
      <text x="${baseLineL+(i*2+1)*rectW}" y="${baselineT+20}" fill="black">${data[i].label}</text>
      <text x="${baseLineL+(i*2+1)*rectW}" y="${baselineT - (data[i].value * 100)-15}" fill="black">${data[i].value}</text>
      `;
      s1.innerHTML += html;
    //创建矩形,别忘了命名空间
      var rect = document.createElementNS("http://www.w3.org/2000/svg", "rect");
      rect.setAttribute("width", rectW);
      rect.setAttribute("height",(data[i].value) * 100);
      rect.setAttribute("x", baseLineL + (i*2+1)*rectW);
      rect.setAttribute("y", baselineT - (data[i].value * 100));
      rect.setAttribute("fill", "url(#g" + i + ")");
      trg.appendChild(rect);
    }
//    把trg碎片放在DOM中
    s1.appendChild(trg);
    trg=null;
  }