flat([1, [2, 3, [4]], [5, 6]]) // 返回 [1,2,3,4,5,6]
const flat = (arr, count) => {
let result = [];
if(!Array.isArray(arr) || typeof count !== 'number') return result;
if(count <= 0) return arr;
let flag = true;
arr.forEach(v => {
if(Array.isArray(v)) {
result.push(...v);
flag = false;
} else {
result.push(v);
}
})
if(!flag) {
result = flat(result, count-1);
}
return result;
}
reduce簡化版
const flat = (arr, count) => {
if(!Array.isArray(arr)) {
throw new Error('Must input a Array!!!');
}
return count > 0 ? arr.reduce((acc, cur) => acc.concat(
Array.isArray(cur) ? flat(cur, count - 1) : cur
), []) : arr;
}
