JSFiddle - React, Tailwind, and code Playground

HTML

<div id="text.header" class="countDiv"></div>
<div id="text.content" class="countDiv"></div>

JavaScript

var array2=new Array();
var array1 = [1,2];
$(".countDiv").each(function(){
   array2.push($(this).attr("id"));
});
                  
for(i=0; i<array1.length; i++){
    document.getElementById(array2[i]).innerHTML=(array1[i]);
}