1. 怎么让 ECharts 图表向左移动起来？
上一篇写到可以通过设置 dataZoom 属性，处理数据太多的情况下图表的展示。有时候我们可能需要让图表有一个从右向左的动态效果，让图表看起来不那么单调。其实也通过 dataZoom 属性，再加上定时器就能实现上图所示的效果。
2. 代码怎么写呢？
我们直接上代码：
<!-- 为 ECharts 准备一个具备大小（宽高）的 Dom -->
<div id="myCharts" style="width: 600px;height:400px;"></div>
<script src="https://cdn.bootcdn.net/ajax/libs/echarts/4.8.0/echarts-en.min.js"></script>
<script type="text/javascript">
var timer = null;
// X 轴数据
var xAxisData = ["16:00", "16:05", "17:10", "17:15", "17:50", "18:05", "18:15", "18:20", "18:30", "18:40", "18:45", "19:00", "19:05", "19:35", "19:50", "20:00", "20:05", "20:25", "20:50", "20:55", "21:00", "21:05", "21:20", "21:35", "21:40", "21:45", "22:10", "22:20", "22:25", "22:30", "22:40", "22:45", "22:50", "22:55", "23:10", "23:15", "23:20", "23:30", "23:35", "23:40", "23:50", "23:55", "00:10", "00:25", "00:30", "00:35", "00:45", "00:50", "01:00", "01:10", "01:30", "01:35", "02:10", "02:15", "02:20", "02:25", "02:40", "02:45", "03:00", "03:20", "03:35", "03:50", "03:55", "04:00", "04:10", "04:15", "04:20", "04:30", "04:35", "04:50", "04:55", "05:00", "05:05", "05:15", "05:25", "05:30", "05:40", "05:55", "06:00", "06:05", "06:10", "06:20", "06:50", "06:55", "07:00", "07:05", "07:10", "07:15", "07:25", "07:35", "07:40", "07:45", "07:50", "08:00", "08:10", "08:20", "08:30", "08:40", "08:45", "08:55", "09:05", "09:10", "09:20", "09:35", "09:40", "09:50", "10:00", "10:05", "10:15", "10:25", "10:35", "10:40", "10:45", "10:50", "10:55", "11:00", "11:20", "11:45", "12:05", "12:20", "12:25", "12:35", "12:55", "13:00", "13:05", "13:10", "13:25", "13:30", "13:55", "14:10", "14:20", "14:30", "14:45", "15:00", "15:05", "15:15", "15:20", "15:25"];
// 需要渲染的 series 数据
var seriesData = [0.93, 0.69, 0.65, 0.69, 1.21, 1.23, 0.63, 0.62, 1.16, 0.65, 1.16, 0.62, 0.85, 1.26, 0.67, 0.65, 1.33, 0.96, 0.61, 0.8, 0.85, 0.97, 1.14, 0.65, 0.86, 0.95, 1.1, 1.18, 0.62, 1.32, 1.19, 0.68, 0.67, 0.65, 0.68, 1.29, 0.65, 1.13, 0.87, 0.96, 0.64, 0.63, 1.24, 0.66, 0.66, 0.87, 1.13, 0.85, 0.99, 1.05, 1.35, 1.33, 0.67, 0.65, 0.65, 1.02, 1.08, 0.71, 0.65, 1.28, 1.35, 0.77, 0.94, 1.31, 1.11, 0.66, 0.9, 1.32, 0.68, 0.66, 0.72, 1.11, 0.65, 0.64, 0.64, 0.83, 1.24, 0.96, 1.11, 0.64, 1.31, 0.6, 0.62, 0.76, 0.63, 0.82, 1.01, 1.32, 1.24, 1.13, 0.84, 1.2, 0.65, 0.91, 0.79, 1.3, 1.27, 1.18, 0.65, 0.63, 1.17, 1.25, 0.7, 1.21, 0.89, 1.39, 1.02, 0.68, 0.69, 1.04, 0.67, 1.06, 1.31, 1.32, 1.2, 0.68, 1.4, 1.28, 0.9, 0.69, 1.38, 1.13, 1.04, 0.79, 0.71, 0.71, 1.2, 1.38, 0.76, 1.35, 0.82, 1.03, 1.29, 1.49, 0.69, 0.74, 0.75, 0.72];
// 基于准备好的 dom，初始化 echarts 实例
var myChart = echarts.init(document.getElementById('myCharts'));
// 指定图表的配置项和数据
var option = {
tooltip: {trigger: 'axis',},
dataZoom: [
{
type: 'slider',
show: false,
realtime: true,
startValue: 0,
endValue: 30, // 初始显示 index0-30 的数据, 可根据你的数据量设置
filterMode: 'none',
},
],
xAxis: {
show: true,
boundaryGap: false,
data: xAxisData
},
yAxis: [
{type: 'value'},
],
series: [
{
type: 'line',
itemStyle: {color: '#188df0',},
areaStyle: {
// 渐变色
color: new echarts.graphic.LinearGradient(0, 0, 0, 1, [
{
offset: 0,
color: '#188df0',
},
{
offset: 1,
color: '#83bff6',
},
]),
},
data: seriesData
},
],
};
// 使用刚指定的配置项和数据显示图表
myChart.setOption(option);
var startNumber = 0;
// 有多少条数据
var xAxisDatalen = xAxisData.length;
// len 的值, 可以根据你的数量量设置, 不要超过 xAxisDatalen 的值, 不然不会动
var len = 30;
timer && clearInterval(timer);
timer = setInterval(function () {if (startNumber === xAxisDatalen - len) {startNumber = 0;}
myChart.dispatchAction({
type: 'dataZoom',
startValue: startNumber,
endValue: startNumber + len,
});
startNumber++;
}, 1000);
</script>需要注意的是：初始的 endValue 的值要跟 len 的值相同，不然会有明显的抖动。还有就是 len 的值不要超过 xAxisDatalen 的值，也就是总的数据有多少条，不然不会有移动的效果。
3. 示例代码下载
可以复制以上代码运行查看使用效果，也可以到 GitHub: https://github.com/Jackyyans/code123 下载，更多示例将会持续更新，欢迎关注。