JSFiddle - React, Tailwind, and code Playground

JavaScript

var products = [  
{ id: 1, groups: [ { id: 1.1, selected: true }, { id: 1.2, selected: false }]}, 
{ id: 2, groups: [ { id: 2.1, selected: false }, { id: 2.2, selected: true }]} ];


const selectgroupid = products.map(x => (x.groups.find(g=> g.selected)).id);

console.log(selectgroupid);