Where's the mistake?

Question

https://code.sololearn.com/Wme06kL86ld0/?ref=app

Answer 1

here...

window.onload = function(){

alert("solve pls");
var month = new Date();

var now = month.getMonth()
switch(now){
case 0:
now = "January";
break ;
case 1:
now = "February";
break ;
case 2:
now = "March";
break ;
case 3:
now = "April";
break ;
case 4:
now = "May";
break ;
case 5:
now = "June";
break ;
case 6:
now = "July";
break ;
case 7:
now = "August";
break ;
case 8:
now = "September";
break ;
case 9:
now = "October";
break ;
case 10:
now = "November";
break ;
case 11:
now = "December";

}

document.write(now)

}

Answer 2

It works when it's december

UPDATE: Just ran it. It also appears that document.body is null at the time when the js is executed. So either that document.body.innerhtml = must be replaced with something like document.write(), or the code should be placed in a function that is executed after the document is loaded.