//文件需要引入html2canvas.js、jquery.js

function downLoadImg(){

      var element = $(".orgchart");    // 这个dom元素是要生成img的div容器

        var w = element.outerWidth();    // 设置该容器的宽

        var h = element.outerHeight();    // 设置该容器的高
var canvas = document.createElement("canvas");

        canvas.width = w;    // 设置画布宽&&高

        canvas.height = h ;

        var offsetTop = element.offset().top;    // 获得该容器的上偏移量

        var offsetLeft = element.offset().left;    // 获得该容器的左偏移量

        var context = canvas.getContext("2d");

        context.translate(-offsetLeft, -offsetTop);

        var opts = {

            canvas: canvas,

            width: w,

            height: h

        }

      html2canvas(element, opts).then(function (canvas) {

          setTimeout(function(){

            let a = document.createElementNS('http://www.w3.org/1999/xhtml', 'a');

            a.href = canvas.toDataURL('image/png',1.0)

            a.download = '下载'

            a.click()

          },100)

      })

    }