https://developers.weixin.qq.com/miniprogram/en/dev/api/route/EventChannel.emit.html
EventChannel.emit(string eventName, any args) | Weixin public doc
the doc for Weixin develoers
emitstringargsweixinpublic
https://developers.weixin.qq.com/miniprogram/en/dev/api/route/EventChannel.off.html
EventChannel.off(string eventName, function fn) | Weixin public doc
the doc for Weixin develoers
stringfunctionfnweixinpublic