SOURCE

const data = [
  { country: 'China', gold: 11, silver: 5, bronze: 8 },
  { country: 'Japan', gold: 11, silver: 4, bronze: 5 },
  { country: 'USA', gold: 10, silver: 11, bronze: 9 },
];

let res1 = { country: 'China', medal: 'gold', value: 11 };
let res2 = { country: 'China', medal: 'silver', value: 5 };
let res3 = { country: 'China', medal: 'bronze', value: 8 };

function change(data){
    let res = [1,2];
    
    data.map((item)=>{
        if(item.gold){
            res.push({
                country:item.country,
                medal:'gold',
                value:item.gold
            })
        }
        if(item.silver){
            res.push({
                country:item.country,
                medal:'silver',
                value:item.silver
            })
        }
        if(item.bronze){
            res.push({
                country:item.country,
                medal:'bronze',
                value:item.bronze
            })
        }
    })

    res.forEach(item=>{
        console.log(item);
    })
}
change(data);