工具函数的封装

 
export const flattenArr = (arr) => {     return arr.reduce((map,item)=>{         map[item.id] = item         return map     },{}) }
export const objToArr = (obj) => {     return Object.keys(obj).map(key => obj[key]) }
// 获取父节点 dom 元素 export const getParentNode = (node,parentClassName) => {     let current = node     while(current !== null){         if(current.classList.contains(parentClassName)){             return current         }         current = current.parentNode     }     return false }