Uncaught TypeError: Cannot set property 'innerHTML' of null

Question

var questions = [
'hi',
'fyn',
'Thank u'
];

var num == 0;

var output = document.querySelector("#Student");
output.innerHTML = questions[0];
var inputBox = document.querySelector("#ans");

function showResponse(){
var input = inputBox.value;
if(inputBox.value == "")
{

}
else
{
if(num == 0)
{
output.innerHTML = '${ans} hi';
inputBox.value = "";
++num;
setTimeout(changeQuestion, 2000);
}
else if(num == 1)
{
output.innerHTML = '${ans} fyn';
inputBox.value = "";
++num;
setTimeout(changeQuestion, 2000);
}
}
}

function changeQuestion(){
output.innerHTML = questions[num];
if(num == 2)
{
inputBox.style.display = "none";

}
}
$(document).on('keypress', function(e)
{
if(e.which == 13){
showResponse();
}
})

Answer 1

Wrap your whole code in:

onload = function() {
//code
};

//page must have loaded first to start grabbing elements from it...