基础库：2.16.0
环境：MacOS 开发者工具
效果图：
代码：
let query = wx.createSelectorQuery();
query.select('#cvs').fields({
node: true,
size: true
}).exec(res => {
const canvas = res[0].node;
const ctx = canvas.getContext('2d');
ctx.fillStyle = "rgb(200,0,0)";
ctx.fillRect (10, 10, 100, 100);
})
const canvas = res[0].node; canvas.width=400; canvas.height=400; const ctx = canvas.getContext('2d');