console.log(
  buildUrl("/products?id=3", { id: 1, format: true }) ===
    "/products?id=1&format=true"
);
console.log(
  decodeURIComponent(
    buildUrl("/products?id=3", { id: [1, 2], format: true })
  ) === "/products?id[]=1&id[]=2&format=true"
);