wxhuanart/miniprogram/utils/watch.ts

function watch(
  this: {
    data: Record<string, string>
  } & any,
  key: string,
  callback: (val: any) => void,
) {
  console.log(this, '555')
  // 先执行一次watch
  callback.call(this, this.data[key])
  let that = this
  let tmpData = this.data[key]

  Object.defineProperty(this.data, key, {
    set: function (value) {
      tmpData = value
      callback.call(that, value)
      console.log('item change', value, key)
    },
    get: function () {
      return tmpData
    },
  })
}
export default watch