arr.flat(depth) @parame depth — The maximum recursion depth默认1
- ES5
function flatten(arr){let n=arr.lengthlet result=[]for(let i=0;i<n;i++){if(Array.isArray(arr[i])){result=result.concat(flatten(arr[i]))}else{result.push(arr[i])}}return result
}
- ES6
function flatten(arr) {while (arr.some(item => Array.isArray(item))) {arr = [].concat(...arr);//展开一层}return arr;
}
