JSFiddle - React, Tailwind, and code Playground

HTML

<div class='c1'></div>
<div></div>
<span></span>
<a href=""></a>

JavaScript

function scanDOM(){
	var a = document.getElementsByTagName('*')
  var childNodes = document.body.childNodes
  
  var count = 0;
  var count1 = 0;
  var count2 = 0;
  var count3 = 0;
  var count4 = 1;
  
  var arr = []
   
  for(var i = 0; i < a.length; i++){
  	if(a[i].tagName == 'DIV'){
    count++
    }
    
    if(a[i].tagName == 'SPAN'){
    count1++
    }
    
    if(a[i].tagName == 'A'){
    count2++
    }
    
    if(a[i].className){
    	 count3++
       arr.push(a[i].className)
    }
    
  }
   console.log('Элементов с классом ' + arr[0] + ': '+ count4)
  	console.log('Тэгов div' + ': ' +count)
    console.log('Тэгов span' + ': ' +count1)
    console.log('Тэгов a' + ': ' +count2)
    
    
     for (var i = 0; i < childNodes.length; i++) {
   		if(childNodes[i].nodeType == 3){
   			count4++
   }
	}
  
  console.log('Текстовых узлов: ' + count4)
}
scanDOM()