一些js逻辑题

1.改成如下那种样子的

var animals = [
 { name: 'lili', species: 'dog' },
 { name: 'mimi', species: 'cat' },
 { name: 'jone', species: 'dog' },
 { name: 'kity', species: 'rabbit' },
 { name: 'tom', species: 'fish' },
 { name: 'jetty', species: 'cat' }
]
//获取所有的狗

/*获取下面的数据
{
    dog: ['lili', 'jone'],
    cat: ['mimi', 'jetty'],
    rabbit: ['kity'],
    fish: ['tom']
}
*/

写一个函数

function getDogs(animalsList) {
        let animalsObj = {};
        animalsList.forEach(item => {
            if (!animalsObj[item.species]) {
                animalsObj[item.species] = [];
            }
            animalsObj[item.species].push(item.name);
        });
        return animalsObj;
    }

2.

arr = [1, 2, [3, [4, [5, [6, 7, 8, [9]]]]]]改成[1,2,3,4,5,6,7,8,9]

const isArr = Array.isArray;

    function f(arr) {
        if (!isArr(arr)) {
            return arr;
        }
        let newA = [];
        arr.forEach(item => {
            if (isArr(item)) {
                newA = newA.concat(f(item));
            } else {
                newA.push(item);
            }
        });
        return newA;
    }

    let arr = [1, 2, [3, [4, [5, [6, 7, 8, [9]]]]]];
    console.log(f(arr));