Why not defined? Why this error?

Question

https://code.sololearn.com/We60IzF1Ni05/?ref=app

Answer 1

Can anyone help?

Answer 2

Is it your code?

The solution is:
var img = document.getElementsByTagName("img");

Answer 3

I wrote up this code only. I am not sure why still is it throwing errors?

Answer 4

Bishwajit Khanra if you would write your own then you could know why. There you cannot really see what is wrote.