中间件-缓存加载函数

/*
缓存加载函数
cacheLen：最多缓存多少个接口
id：唯一值
name：方法名
syncFunc：加载函数
 */
// 缓存最近的20个接口
const methodCacheArr = []
let cacheLen = 20
try {
  const arr=JSON.parse(localStorage.getItem('queryNoError'))
  arr.forEach(function (item) {
    methodCacheArr.push(item)
  })
  cacheLen=arr.length+20;
}catch (e) {
  
}

function getCacheIndex (val, key) {
  let has = -1
  for (let i = methodCacheArr.length - 1; i >= 0; i--) {
    if (val === methodCacheArr[i][key]) {
      has = i
      break
    }
  }
  return has
}

export function getCache (name) {
  const has = getCacheIndex(name, 'name')
  if (has > -1) {
    return methodCacheArr[has].res
  } else {
    return null
  }
}

export function delCache (name) {
  const has = getCacheIndex(name, 'name')
  if (has > -1) {
    methodCacheArr.splice(has, 1)
  }
}

export async function limitCache ({id, name, useCache,queryNoError}, syncFunc) {
  const has = getCacheIndex(id, 'id')

  if (useCache && has > -1) {
    if(typeof useCache !== 'number'){
      useCache=300;
    }
    if (useCache * 1000 + methodCacheArr[has].time > +new Date()) {
      return methodCacheArr[has].res
    }
  }
  let res = await syncFunc()
  //更新缓存
  if (res && res.flag === 'S') {
    if (has > -1) {
      methodCacheArr.splice(has, 1)
    }
    methodCacheArr.push({
      id: id,
      queryNoError:queryNoError,
      name: name,
      time: +new Date(),
      res: res
    })
    if (methodCacheArr.length > cacheLen) {
      methodCacheArr.splice(0, 1)
    }
    if(queryNoError){
      const arr=methodCacheArr.filter(function (item) {
        return item.queryNoError;
      })
      if (arr.length > 20) {
        arr.splice(0, 1)
      }
      localStorage.setItem('queryNoError',JSON.stringify(arr))
    }
  }else if(has > -1&&queryNoError){
    //兼容查询失败的情况
    return methodCacheArr[has].res;
  }
  return res
}