js实现ECharts图表的下载

方法一：
ECharts自带的方法，在toolbox配置项，feature里面有一个saveAsImage方法：

<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>吾学网 &#8211; 5xue.cc &#8211; js实现ECharts图表的下载</title>
	<!--引入echarts.js -->
	<script type="text/javascript" src="https://cdn.staticfile.org/echarts/4.3.0/echarts.min.js"></script>
</head>
<body>
	<!-- 为ECharts准备一个容器 -->
	<div id="container" style="width: 600px;height:400px;"></div>
	<script type="text/javascript">
		//初始化echarts实例
		var myChart = echarts.init(document.getElementById('container'));
		//配置图表项和数据
		var option = {
			title: {
				text: '第一个 ECharts 实例'
			},
			tooltip: {},
			legend: {
				data:['销量']
			},
			xAxis: {
				data: ["衬衫","羊毛衫","雪纺衫","裤子","高跟鞋","袜子"]
			},
			yAxis: {},
			toolbox: {
				show: true,
				feature: {saveAsImage: {}}
			},
			series: [{
				name: '销量',
				type: 'bar',
				data: [5, 20, 36, 10, 10, 20]
			}]
		};
		//绘制图表
		myChart.setOption(option, true);
	</script>
</body>
</html>

<!DOCTYPE html>

<html>

<head>

<title>吾学网 – 5xue.cc – js实现ECharts图表的下载</title>

</head>

<body>

//初始化echarts实例

var myChart = echarts.init(document.getElementById('container'));

//配置图表项和数据

var option = {

title: {

text: '第一个 ECharts 实例'

tooltip: {},

legend: {

data:['销量']

xAxis: {

data: ["衬衫","羊毛衫","雪纺衫","裤子","高跟鞋","袜子"]

yAxis: {},

toolbox: {

show: true,

feature: {saveAsImage: {}}

series: [{

name: '销量',

type: 'bar',

data: [5, 20, 36, 10, 10, 20]

}]

};

//绘制图表

myChart.setOption(option, true);

</script>

</body>

</html>

查看样例

方法二：
Echarts提供一个接口getDataURL，通过它可以导出图表图片，返回一个 base64 的 URL。实现思路：

通过getDataURL()获取图片的base64编码字符；
字符解码，并转换成Blob对象；
通过Blob对象创建URL对象；
利用触发下载操作；

代码如下：

<!DOCTYPE html>
<html>
<head>
	<meta charset="utf-8">
	<title>吾学网 &#8211; 5xue.cc &#8211; js实现ECharts图表的下载</title>
	<!--引入echarts.js -->
	<script type="text/javascript" src="https://cdn.staticfile.org/echarts/4.3.0/echarts.min.js"></script>
</head>
<body>
	<!-- 为ECharts准备一个容器 -->
	<div id="container" style="width: 600px;height:400px;"></div>
	<input type="button" value="下载图表" onclick="saveImage()" />
	<script type="text/javascript">
		//初始化echarts实例
		var myChart = echarts.init(document.getElementById('container'));
		//配置图表项和数据
		var option = {
			title: {
				text: '第一个 ECharts 实例'
			},
			tooltip: {},
			legend: {
				data:['销量']
			},
			xAxis: {
				data: ["衬衫","羊毛衫","雪纺衫","裤子","高跟鞋","袜子"]
			},
			yAxis: {},
			series: [{
				name: '销量',
				type: 'bar',
				data: [5, 20, 36, 10, 10, 20]
			}]
		};
		//绘制图表
		myChart.setOption(option, true);

		function base64ToBlob(code) {
			let parts = code.split(';base64,');
			let contentType = parts[0].split(':')[1];
			let raw = window.atob(parts[1]);
			let rawLength = raw.length;
			let uInt8Array = new Uint8Array(rawLength);
			for (let i = 0; i < rawLength; ++i) {
				uInt8Array[i] = raw.charCodeAt(i);
			}
			return new Blob([uInt8Array], { type: contentType });
		}
		
		function saveImage() {
			let content = myChart.getDataURL();
			let aLink = document.createElement('a');
			let blob = this.base64ToBlob(content);
			let evt = document.createEvent("HTMLEvents");
			evt.initEvent("click", true, true);
			aLink.download = "ECharts报表.png";
			aLink.href = URL.createObjectURL(blob);
			aLink.dispatchEvent(new MouseEvent('click', { bubbles: true, cancelable: true, view: window}));
		}
	</script>
</body>
</html>