H5 dom元素保存为图片

一、使用插件html2canvas：https://github.com/niklasvh/html2canvas

具体代码：

1.html

<div class="test">

      </div>
      <img class="down" src="" />

2.js
//创建一个新的canvas
    var canvas2 = document.createElement("canvas");
    let _canvas = document.querySelector('.test');
    var w = parseInt(window.getComputedStyle(_canvas).width);
    var h = parseInt(window.getComputedStyle(_canvas).height);
    //将canvas画布放大若干倍，然后盛放在较小的容器内，就显得不模糊了
    canvas2.width = w * 2.2;
    canvas2.height = h * 2.2;
    canvas2.style.width = w + "px";
    canvas2.style.height = h + "px";
    //可以按照自己的需求，对context的参数修改,translate指的是偏移量
    //  var context = canvas.getContext("2d");
    //  context.translate(0,0);
    var context = canvas2.getContext("2d");
    context.scale(2,2);
    html2canvas(document.querySelector('.test'),{
     	canvas:canvas2
    }).then(function(canvas) {
      document.body.appendChild(canvas);
    document.querySelector('canvas').style.display = "none"
      //canvas转换成url，然后利用a标签的download属性，直接下载，绕过上传服务器再下载
      document.querySelector(".down").setAttribute('src',canvas.toDataURL());
      
			document.querySelector(".test" ).style.display = "none";
    });

　　二、使用dom-to-image

npm下载：https://www.npmjs.com/package/dom-to-image