wx.createCanvasContext()停止维护替代写法

wx.createCanvasContext()停止维护，可以使用NodesRef.context替代

代码示例

<canvas id="ssd" canvas-id="ssd"></canvas>

let canvasBox = null;

// 写法一
canvasBox = wx.createCanvasContext("ssd");
// 写法二
wx.createSelectorQuery()
      .select("#ssd")
      .context(function (res) {
        console.log("节点实例：", res); // 节点对应的 Canvas 实例。
        canvasBox = res.context;
      })
      .exec();

相关文档链接
createCanvasContext：https://developers.weixin.qq.com/miniprogram/dev/api/canvas/wx.createCanvasContext.html
createSelectorQuery：https://developers.weixin.qq.com/miniprogram/dev/api/wxml/NodesRef.context.html