JSFiddle - React, Tailwind, and code Playground

JavaScript

var newArr = [];
var array=[
{Id:"001",qty:1},
{Id:"002",qty:2},
{Id:"001",qty:2},
{Id:"003",qty:4}
];
$.each(array,function(index,element){
    if(newArr[element.Id]==undefined)
        newArr[element.Id] =0;
    newArr[element.Id] += element.qty;
});
console.log(newArr);