What's wrong with this code?

Question

https://code.sololearn.com/W3nSbcwlAC1X/?ref=app

Answer 1

This is a code from w3 schools right? Try placing the script inside the HTML tab - because to manipulate DOM with JS tab you have to wrap the whole JS code with window.onload method

Answer 2

script tags at head runs before the DOM exists.

Move the script tags and all js code snippets to just before the closing tag of body.

https://code.sololearn.com/W8qiO41gHNfu/?ref=app

Answer 3

Is that correct now?

Answer 4

No, it is not working.