获取具有非空数组作为值的属性的 object 键

Question

I have an array:

417: Array(2)
0: 24301
1: 24300
length: 2
__proto__: Array(0)
418: [24562]
length: 419
__proto__: Array(0)

Now, i need to get all those keys from this array arr whose length is greater than 0. In this case, i need the answer as ['417','418'] .

I have tried to filter using each loop and .length of each element as:

My code is as:

        console.log(arr_of_sel_units);
        $.each(arr_of_sel_units, function(k, v) {
            console.log(v.length)
        });

But, it is returning error Cannot read property 'length' of undefined

Answer 1

If proper datatype ( Object ) used for arr , you may do Array.prototype.filter() across Object.keys() (however, it will work for your notation just as well as array is essentially an object):

 const src = {a: ['1','2','3' ], b: [], c: ['1' ], d: []}, result = Object.keys(src).filter(key => src[key].length) console.log(result)

Answer 2

Use Object.entries , filter

 let arr = []; arr["a"] = ["1", "2", "3"]; arr["b"] = []; arr["c"] = ["1"]; arr["d"] = []; const res = Object.entries(arr).filter(([, value]) => value.length > 0).map(([key]) => key); console.log(res);