@fanx/wxstore/utils/diff.js

wechat miniprogram store manager

import {
  type,
  OBJECT,
  ARRAY
} from './utils'
/**
 * diff
 * @param {*} current 当前数据
 * @param {*} pre 原数据
 * @param {*} prefix diff key 前缀
 * @param {*} performance 是否开始数组performance模式，开始后可对push类型数组diff优化，若非push改变的数组可能会出现数据错误
 */
export default function diff (current, pre, prefix = '', performance) {
  const diffObj = {}
  if (type(pre, ARRAY) && type(current, ARRAY)) {
    if (current.length < pre.length) {
      // 数据length比原数据小，全替换
      diffObj[prefix] = current
    } else {
      // 数据length比原数据大
      if (!performance) {
        // 非性能模式下数组每一项深层diff
        for (let i = 0; i < pre.length; i++) {
          Object.assign(diffObj, diff(current[i], pre[i], `${prefix ? `${prefix}[${i}]` : `[${i}]`}`, performance))
        }
      }
      if (current.length > pre.length) {
        // 性能模式下数组push
        for (let i = pre.length; i < current.length; i++) {
          diffObj[`${prefix}[${i}]`] = current[i]
        }
      }
    }
  } else if (type(pre, OBJECT) && type(current, OBJECT)) {
    // 对象
    const keys = Object.keys(current)
    keys.forEach((key) => {
      Object.assign(diffObj, diff(current[key], pre[key], `${prefix ? `${prefix}.${key}` : key}`, performance))
    })
  } else if (prefix && current !== pre) {
    // 非数组非对象
    diffObj[prefix] = current
  }
  return diffObj
}