JS数组扁平化

JS实现将数组进行扁平化处理，即将多维数组展开为一维数组

方法一、递归

function flatten(arr){
    let result = [];
    for(let i=0;i<arr.length;i++){
        if(Array.isArray(arr[i])){
            result = result.concat(flatten(arr[i]));
        }
        else{
            result.push(arr[i]);
        }
    }
    return result;
}
 console.log(flatten(['a', ['b', 'c', [7, 8]],[4,5,[6]]]))

方法二、arrary.reduce

function flatten2(arr) {
   return  arr.reduce((accumulator,currentValue)=>
         accumulator.concat(Array.isArray(currentValue) ? flatten2(currentValue) : currentValue),
        []);
}
console.log(flatten2(['a', ['b', 'c', [7, 8]],[4,5,[6]]]));

考察升级：要求这个函数接受一个参数来确定扁平化深度

function flatten_deep(arr, deep) {
    let result = [];
    if (Array.isArray(arr) && deep > 0) {
        for (let i = 0; i < arr.length; i++) {
            result = result.concat(flatten_deep(arr[i], deep - 1));
        }
    }
    else {
        result.push(arr);
    }
    return result;
}

console.log(flatten_deep(['a', ['b', 'c', [7, 8]],[4,5,[6,['dd','whidhw']]]],3));