const flattenArray = arr => {
const flattened = [].concat(...arr);
return flattened.some(v => Array.isArray(v))?flattenArray(flattened):flattened;
}
const arr = [1,[2,3,[3.1,3.2]],4];
console.log(flattenArray(arr)); //[1, 2, 3, 3.1, 3.2, 4]
原文：https://www.cnblogs.com/beesky520/p/9210946.html