why i cannot call this function?

Question

function a() {
var d = new Date()
var a = d.getSeconds()
var b = d.getMilliseconds()
document.body.innerHTML = `${a}:${b}`
}
a()

Answer 1

5th line is invalid. You need to do this:
document.getElementsByTagName("body")[0].innerHTML = "Something";

You also need to wait until the DOM loads the page, so you have to do something like this:
window.onload = a;
and remove the line with a();

Answer 2

Oh, I see.
Fixed.

Answer 3

S Pace Oh, I am not an expert in JS, so I wrote that just to make sure.

Answer 4

I am not an expert @Jan Štěch

Answer 5

Jan Štěch

document.body works !

Answer 6

https://code.sololearn.com/WxwMoJJlUM8B/?ref=app