1.利用join的可迭代性转换多重数组const_flatten = arr => {// 补全代码arr.forEach((ele,index) =>{if(typeof ele==="object"){arr1=ele.join(",").split(",").map((x)=>+x);arr.splice(index,1,...arr1);}})returnarr;}2.利用while循坏遍历多重数组const_flatten = arr => {// 补全代码let count1=0;while(tru...