tt-mp/core/helpers/computedBehavior.js

一套组件化、可复用、易扩展的头条小程序 UI 组件库

import isEmpty from './isEmpty'
import shallowEqual from './shallowEqual'

const ALL_DATA_KEY = '**'

const trim = (str = '') => str.replace(/\s/g, '')

export default Behavior({
  lifetimes: {
    attached() {
      this.initComputed()
    },
  },
  definitionFilter(defFields) {
    const { computed = {} } = defFields
    const observers = Object.keys(computed).reduce((acc, name) => {
      const [field, getter] = Array.isArray(computed[name])
        ? computed[name]
        : [ALL_DATA_KEY, computed[name]]
      return {
        ...acc,
        [field]: function (...args) {
          if (typeof getter === 'function') {
            const newValue = getter.apply(this, args)
            const oldValue = this.data[name]
            if (!isEmpty(newValue) && !shallowEqual(newValue, oldValue)) {
              this.setData({ [name]: newValue })
            }
          }
        },
      }
    }, {})

    Object.assign((defFields.observers = defFields.observers || {}), observers)
    Object.assign((defFields.methods = defFields.methods || {}), {
      initComputed: function (data = {}, isForce = false) {
        if (!this.runInitComputed || isForce) {
          this.runInitComputed = false
          const context = this
          const result = { ...this.data, ...data }
          Object.keys(observers).forEach((key) => {
            const values = trim(key)
              .split(',')
              .reduce((acc, name) => [...acc, result[name]], [])
            observers[key].apply(context, values)
          })
          this.runInitComputed = true
        }
      },
    })
  },
})