Cannot iterate through an html collection using GetElementsByClass

Question

function startup() {

   var fontButtons = document.getElementsByClassName("fontsizer")
   console.log(fontButtons)
   console.log(fontButtons.length)

   for(i=0; i < fontButtons.length; i++) {
      console.log()
   }

}   

when i run this console.log(fontButtons) gives me an htmlCollection but the length is 0, how is this possible?

I can't iterate over something that has a length of 0, but it still gives me the collection of the first console.log of this