wxml <send-coupon bindcustomevent="getcoupon" sign="{{card.sign}}" send_coupon_merchant="{{card.send_coupon_merchant}}" send_coupon_params="{{card.send_coupon_params}}" send-coupon-params="{{card.send_coupon_params}}">领取</send-coupon> js getcoupon: function (params) {   console.log(params); }