JSFiddle - React, Tailwind, and code Playground

by nevkatz

HTML

<div id="root">

</div>

JavaScript

var teacher_objects = [{
 data: {
   classes:[{}]
 }
},
{
  data: {
    classes:[{},{}]
  }
}
];

 let num_classes = teacher_objects.reduce(function(ttl,cur){
       return ttl + cur.data.classes.length;
    },0);
    
 document.querySelector('#root').textContent = num_classes;