let data = [ {id: 1, country: 'Germany', population: 83623528}, {id: 2, country: 'Austria', population: 8975552}, {id: 3, country: 'Switzerland', population: 8616571} ]; let dictionary = Object.assign({}, ...data.map((x) => ({[x.id]: x.country}))); // {1: "Germany", 2: "Austria", 3: "Switzerland"}