页面结构文件wxm中引入canvas节点

<canvas bindtouchend="onTap" style="width:{{cvs.width}}px;height:{{cvs.height}}px;" canvas-id="canvas"></canvas>

页面逻辑文件js中引入mcaptcha

假设mcaptcha.js文件放在utils下边
let Mcaptcha = require('../../utils/mcaptcha.js');
............
data:{
    cvs:{
        width:120,
        height:35
    }
},
onReady: function () {
    this.mcaptcha = new Mcaptcha({
        el: 'canvas',
        width: this.data.cvs.width,
        height: this.data.cvs.height,
        code: "afced"
    );
},
//刷新图形验证码
onTap(){
    this.mcaptcha.refresh("ftgcv");
},
..........

参考文章

• canvas实现图形验证码小插件