const fakeDataObj = fakeData2.reduce((obj, item) => Object.assign(obj, { [item.name]: item.valueOf() }), {}) const str = '4556' as string; console.log(fakeDataObj['4556' as keyof typeof fakeDataObj]); //back to array const new array = [] for (const elem in fakeDataObj.data) { newArray.push(fakeDataObj.data[elem as keyof typeof fakeDataObj.data]) }