JSFiddle - React, Tailwind, and code Playground

JavaScript

json={"1": {
  "id": 1,
  "name": "lola",
  "phones": [{
    "mobile": "xxx",
    "home": "xxx",
    "work": "xxx",
    "hardwares": [{
      "provider": "samsung",
      "model": "galaxy S5"
    }, {
      "provider": "apple",
      "model": "iphone 6"
    }]
  }]
}};


json["1"].phones.push({
    mobile: "xxxxx",
    home: "xxxxx",
    work: "xxxxx",
    "hardwares": []
  });
  
  json["1"].phones[0]['hardwares'].push({
    provider: "provider 0",
    model: "model 0",
  });
  json["1"].phones[1]['hardwares'].push({
    provider: "provider 1",
    model: "model 1",
  });
  
console.log( JSON.stringify(json) );