2018-6-21_《ES6數組扁平化函數》

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]