小程序ios环境下finally报错

解决办法

判断是否存在finally方法，不存在则在Promise原型上添加finally方法

// 兼容ios真机环境下Promise对象不存在finally方法
if (!Promise.prototype.finally) {
  Promise.prototype.finally = function(callback) {
    this.then(res => {
      callback && callback(res)
    }, error => {
      callback && callback(error)
    })
  }
}

Promise finally实现

Promise.prototype.finally = function (callback) {
  let P = this.constructor;
  return this.then(
    value  => P.resolve(callback()).then(() => value),
    reason => P.resolve(callback()).then(() => { throw reason })
  );
};