Working with JSON & External APIs

Parsing JSON

interface User { id: number; name: string; }

const raw = `[{"id":1,"name":"Alice"}]`;
const users: User[] = JSON.parse(raw);

Fetch API (browser & node ≥18)

async function getUser(id: number): Promise<User> {
  const resp = await fetch(`https://jsonplaceholder.typicode.com/users/${id}`);
  if (!resp.ok) throw new Error('Network error');
  const data = await resp.json();
  return data as User;
}

Runtime Validation with zod

npm i zod

import { z } from "zod";
const UserSchema = z.object({ id: z.number(), name: z.string() });
const parsed = UserSchema.parse(await resp.json());