JSFiddle - React, Tailwind, and code Playground

JavaScript

var test = {
    "id": "123",
    "discount": [
        {
            "abc": "xx",
            "bcd": "xx",
             "mc": {
            "dca": "xx",
            },
            "typ": "xx",
            "state": "xx",
            "mns": []
        }
     ]
     };
     
     for(var i=0;i<test.discount.length;i++){
       var disc = test.discount[i];
       disc['newElement']='SomeValue';      
     }
     
     console.log(test);