Why is "for" statement needed below?

Question

What is the array length in this code? Is it the length of hello or p or what?

<p> hello </p>
Var arr = document.getElementsByTagName("p");
For (var x=0; x<arr.length; x++)
{
arr[x].innerHTML = "Hi there";
}

Answer 1

Because getElementsByTagName gives an array of elements ,so all the p tag in document are selected now and for loop is adding to each p tag Hi there ,if you just want to add Hi there to a particular p tag you could do by arr[3].innerHTML="whatever"

Answer 2

Thank you Abhay😃

Answer 3

Mnemonic trick:

getElementById => return once element
getElementsByTagName => return array-like of elements (not an array technically, but act almost as an array -- duck typing)

Observe: what's to notice?
If once element returned, no "s" at the end of "getElementBy..."
If many elements returned, "s" at the end of "getElementsBy..."

Hope this could help ;)