/*
* logic:
* 1. Configure WeChat js sdk config to ensure normal use of WeChat js sdk in the background.
* 2. Obtain the parameters needed to obtain prepay_id and pass them to /pay/unifiedorder to obtain unified ordering information.
* 3. Obtain paySign according to the signatures of' appid',' timeStamp',' nonceStr',' package' and' signType' = 'MD5' of the order information.
* 4. At this point, WeChat payment is over.
*
*/