为什么我在 output 以及答案中变得不确定？

Question

let array = [1, 2, 3];
function lastElement(array) 
{

    if (array === []) 
    {
        return null;
    }
    else 
    {
        return array.slice(-1);
    }
}

Answer 1

you are doing it in the wrong way, you cannot check if an array is empty like you did.

function lastElement(array) {
  if(array.length == 0) return null
  return array[array.length - 1]
}

array.length returns the count of elements inside an array.

You also need not to add an else statement because if we are returning from a functions, the code below that line does not get executed.

Answer 2

Hi I seen you are facing the issue of checking array and slice the data also.

Simply if you want to check the array is empty or not you will using something like this in the js

To get the last element of an array you can use

 let array = [1, 2, 3]; console.log(array.length-1);

To Check array is empty and also get the last element of an array

 let array = [1, 2, 3]; function lastElement(array) { if(array.length == 0) return null return array[array.length - 1] } console.log(lastElement(array))

To know more about slice which you have used in the above problem click here