reduce数组扁平化和递归数组处理

数组扁平化
a = [[0,1],[2,3],[4,[5,6,7]]] ， b =[1,2,3,4,5,6,7]把a转换为b

     let a = [[0,1],[2,3],[4,[5,6,7]]]  
        const newArr = function(arr){
        	return arr.reduce((pre,cur) =>pre.concat(Array.isArray(cur)?newArr(cur):cur),[])
        }
        newArr(a)         //[1,2,3,4,5,6,7]

reduce使用