tencent cloud

// behavior.js
module.exports = Behavior({
  definitionFilter(defFields) {
    defFields.data.from = 'behavior'
  },
})

// component.js
Component({
  data: {
    from: 'component'
  },
  behaviors: [require('behavior.js')],
  ready() {
    console.log(this.data.from) // Here, one would observe that the output is 'behavior' rather than 'component'.
  }
})

// behavior3.js
module.exports = Behavior({
  definitionFilter(defFields, definitionFilterArr) {},
})

// behavior2.js
module.exports = Behavior({
  behaviors: [require('behavior3.js')],
  definitionFilter(defFields, definitionFilterArr) {
    // definitionFilterArr[0](defFields)
  },
})

// behavior1.js
module.exports = Behavior({
  behaviors: [require('behavior2.js')],
  definitionFilter(defFields, definitionFilterArr) {},
})

// component.js
Component({
  behaviors: [require('behavior1.js')],
})

// behavior.js
module.exports = Behavior({
  lifetimes: {
    created() {
      this._originalSetData = this.setData // Original setData
      this.setData = this._setData // Encapsulated setData
    }
  },
  definitionFilter(defFields) {
    const computed = defFields.computed || {}
    const computedKeys = Object.keys(computed)
    const computedCache = {}

    // Compute "computed"
    const calcComputed = (scope, insertToData) => {
      const needUpdate = {}
      const data = defFields.data = defFields.data || {}

      for (const key of computedKeys) {
        const value = computed[key].call(scope) // Compute new value
        if (computedCache[key] !== value) needUpdate[key] = computedCache[key] = value
        if (insertToData) data[key] = needUpdate[key] // Direct insertion into data, an operation required only during initialization
      }

      return needUpdate
    }

    // Overwrite setData method
    defFields.methods = defFields.methods || {}
    defFields.methods._setData = function (data, callback) {
      const originalSetData = this._originalSetData // Original setData
      originalSetData.call(this, data, callback) // Perform setData on data
      const needUpdate = calcComputed(this) // Compute "computed"
      originalSetData.call(this, needUpdate) // Perform setData on "computed"
    }

    // Initialize "computed"
    calcComputed(defFields, true) // Compute "computed"
  }
})

const beh = require('./behavior.js')
Component({
  behaviors: [beh],
  data: {
    a: 0,
  },
  computed: {
    b() {
      return this.data.a + 100
    },
  },
  methods: {
    onTap() {
      this.setData({
        a: ++this.data.a,
      })
    }
  }
})

<view>data: {{a}}</view>
<view>computed: {{b}}</view>
<button bindtap="onTap">click</button>