之前在网上找到一个用 <a> 的 download属性下载的方法，确实很简单也很方便，但此方法不支持IE，无奈又找到另一方法。
使用html2canvas将页面转成图，用canvas2image下载
本例使用的版本：
html2canvas@1.0.0-alpha.12
canvas2image@1.0.5
安装
npm install html2canvas canvas2image --save
引入
import html2canvas from 'html2canvas';
require('./canvas2image.js');
canvas2image.js 需要改动一下，以便绑在window上
(function($){
Canvas2Image = function () {
...
}
}
_dataURL 可以用来回显，Canvas2Image.saveAsPNG(canvas) 会直接下载。
Canvas2Image提供了下面几种方法:
Canvas2Image.saveAsImage(canvasObj, width, height, type)
Canvas2Image.saveAsPNG(canvasObj, width, height)
Canvas2Image.saveAsJPEG(canvasObj, width, height)
Canvas2Image.saveAsGIF(canvasObj, width, height)
Canvas2Image.saveAsBMP(canvasObj, width, height)
Canvas2Image.convertToImage(canvasObj, width, height, type)
Canvas2Image.convertToPNG(canvasObj, width, height)
Canvas2Image.convertToJPEG(canvasObj, width, height)
Canvas2Image.convertToGIF(canvasObj, width, height)
Canvas2Image.convertToBMP(canvasObj, width, height)
在vue中可以用$refs 确定DOM；
backgroundColor: null，此句可使转出的图没有白边
methods: {
toImage() {
let _this = this;
html2canvas(this.$refs.index,{
backgroundColor: null
}).then((canvas) => {
let _dataURL = canvas.toDataURL("image/png");
// _this.dataURL = _dataURL;
Canvas2Image.saveAsPNG(canvas)
});
},
