JSFiddle - React, Tailwind, and code Playground

JavaScript

var a = [
   {
      "title":"New Jersey",
      "NFLteams":[
         {
            "Name":"Jets",
            "Conference":"AFC",
         },
         {
            "Name":"Giants",
            "Conference":"NFC",
         }
         ]
   },
   {
      "title":"Massachusetts",
      "NFLteams":[
         {
            "Name":"Patriots",
            "Conference":"AFC",
         }
         ]
   },
   {
      "title":"California",
      "NFLteams":[
         {
            "Name":"Raiders",
            "Conference":"AFC",
         },
         {
            "Name":"49ers",
            "Conference":"NFC",
         },
         {
            "Name":"Chargers",
            "Conference":"AFC",
         }
         ]
   }
];

a.sort(function(a,b){return b.NFLteams.length - a.NFLteams.length}).forEach(function(item){console.log(item.title)});