javascript - CanvasJS 图表 axisX 未定义

Question

我有一个 CanvasJS 图表，我想动态设置它的 stripLine。

chart = new CanvasJS.Chart("chart",
    {
        backgroundColor: "rgba(0,0,0,0)",
        legend: {
            fontColor: "#FFF"
        },
        axisX: [{
            title: "Test axisX title",
            stripLines: [
                {
                    value: 250,
                    color: "#FF0000"
                }
            ],
        }],
        data: [] //Later add datapoints
    });

设置stripLine位置的函数:

var setVerticalLine = function (xPos) {
if (typeof chart !== 'undefined') {
    console.log(JSON.stringify(chart));  //debug info
    console.log("chart.axisX type: " + typeof chart.axisX); //debug info
    chart.axisX[0].stripLines[0].set("value", xPos);
}};

渲染后我调用该函数，但设置不成功。
错误:

Uncaught TypeError: Cannot read property '0' of undefined..."
The debug info: "chart.axisX type: undefined". The dumped chart object contains the axisX: "..."axisX":[{"title":"Test axisX title","stripLines":[{"value":250,"color":"#FF0000"}]}]...

当我在渲染的图表上看到带有标题和带状线的 axisX 时，它怎么会未定义？为什么我无法访问和修改？有人可以帮我解决这个问题吗？

Answer 1

根据documentation , '在使用 set 方法之前应先渲染图表'。在调用 setVerticalLine 之前渲染图表应该可以正常工作。

这是工作代码:

var chart = new CanvasJS.Chart("chart", {	
  backgroundColor: "rgba(0,0,0,0)",
  legend: {
    fontColor: "#FFF"
  },
  axisX: [{
    title: "Test axisX title",
    stripLines: [
      {
        value: 250,
        color: "#FF0000"
      }
    ],
  }],
  data: [] //Later add datapoints
});

chart.options.data.push({type: "line", dataPoints: [{x: 200, y: 100}, {x: 300, y: 50}]}); //Dummy datapoints
chart.render();// Render Chart before using set method

var setVerticalLine = function (xPos) {
  if (typeof chart !== 'undefined') {
    chart.axisX[0].stripLines[0].set("value", xPos);
  }
};

setVerticalLine(220); //Update Stripline value to 220

<script src="https://canvasjs.com/assets/script/canvasjs.min.js"></script>
<div id="chart" style="height: 260px; width: 100%;"></div>