JSFiddle - React, Tailwind, and code Playground

HTML

OLHE NO CONSOLE (F12)

JavaScript

var fields = [
  {
    "Book Name": "Computer Architecture",
    "Category": "Computers",
    "Price": "125.60",
    "Book ID": "1"
  },
  {
    "Book ID": "2",
    "Book Name": "Asp.Net 4 Blue Book",
    "Category": "Programming",
    "Price": "56.00"
  },
  {
    "Price": "210.40",
    "Book Name": "Popular Science",
    "Book ID": "3",
    "Category": "Science"
  }
];
    if(fields.length > 0){
    	var newField = [];
        for(var i = 0; i < fields.length; i++){
            var field = fields[i];
            fields[i]["abobora"] = 'abobora teste';
        }
        var newField = fields;
        //OLHE NO CONSOLE
        console.log(newField);
    }