Why is this code not working?

Question

I am very confused. Please help.(The corresponding HTML is fine.
function setText() {
var a = document.getElementById("demo");
var arr = a.childNodes;
arr[0].innerHTML="Hello! How are you?";
}
setTimeout(setText, 500);

Answer 1

Make loop like: var arr = a.childNodes;
for(var x=0;x<arr.length;x++)