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);

}