What' s wrong in this code?

Question

The error is "cannot change property style of null".
I can' t understand why it doesn' t work...

var l = setInterval(1, o());
var x = 500;
function o() {
x--
var g = document.getElementById('p');
g.style.height = x + 'px';
if (x <= 100) {
clearInterval(l)
}
}

Answer 1

Wrong argument and wrong sequence of arguments passed into setInterval

setInterval accepts two arguments

The second argument is time in millisecond.

The first argument is a callback function.

When you pass a function as callback, just put the function name. Don't add parenthesis, because parenthesis will execute it and you will be passing the executed result instead.

Answer 2

var x = 500;
function o() {
x--
var g = document.getElementById('p');
g.style.height = x + 'px';
if (x <= 100) {
clearInterval(l)
}
}
var l = setInterval(o,1);

try this one.

Answer 3

Thanks Labib Hasan and Gordon, I'll try it