Javascript: Function returning last element of array

Question

I'm taking Colt Steele's Udemy Course titled: "The Web Developer Bootcamp 2020". I have however become stuck on a certain coding exercise. The exercise objective is as follows: Please write a function called lastElement which accepts a single array argument. The function should return the last element of the array(without removing the element). If the array is empty, the function should return null.

I have tried coming up with a solution but cant seem to figure it out. My current best guess is this :

function lastElement (num) {
if (num !== undefined){
    return num[num.length -1];
} return null;

}

I'm interested in knowing why the function I have written doesn't work and some pointers on how I should rethink the function, so that it does work.

Best Regards Andreas

Sazid Ahmed Nassir · Accepted Answer · 2021-07-27 07:28:33Z

2

You can use this:

function lastElement(arr) {
if(arr.length>0){
   return arr[arr.length-1];
} else{
   return null;
}

answered Jul 27, 2021 at 7:28

Sazid Ahmed Nassir

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Comments

IRSHAD · Accepted Answer · 2020-11-29 08:04:59Z

1

Change to this condition.

if (num && num.length>0)

edited Nov 29, 2020 at 8:04

answered Nov 29, 2020 at 7:55

IRSHAD

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1 Comment

IRSHAD Over a year ago

if(num) checks for all 'falsy' values. Check whether 'num' exists.

Nikola Lukic · Accepted Answer · 2022-04-20 16:34:16Z

1

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

edited Apr 20, 2022 at 16:34

Nikola Lukic

4,2746 gold badges51 silver badges81 bronze badges

answered Apr 19, 2022 at 20:25

sgfa erwy

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Comments

Ron · Accepted Answer · 2020-11-29 08:08:26Z

0

change your condition to:

if(num && num.length>0)

additionally, if they decide to enter an argument that is not an array,

if(num && Array.isArray(num) && num.length>0)

answered Nov 29, 2020 at 8:08

Ron

1172 bronze badges

Comments

Saar Seri · Accepted Answer · 2020-11-29 08:22:42Z

0

The problem lies in the difference of truthy and falsy values: Empty array is truthy but undefined is falsy, so []!==undefined is true, but:

num[num.length -1];

means:

num[-1];

which is undefined .

answered Nov 29, 2020 at 8:22

Saar Seri

611 silver badge4 bronze badges

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