Mi viaje Java Full Stack en JavaScript

Guía rápida de Fetch y Axios para solicitudes HTTP en JavaScript, con ejemplos en promesas y async/await, y una introducción a closures y consejos prácticos.

7 sept 2025 • 1 min read • Q2BSTUDIO Team

Inteligencia-Artificial-

Fetch

Fetch es la forma moderna y nativa en JavaScript para realizar solicitudes de red, ya sea para obtener datos de un servidor o para enviar información. Devuelve una promesa y funciona muy bien con JSON.

Ejemplo correcto con promesas: fetch(https://fakestoreapi.com/products) .then(res => res.json()) .then(data => console.log(data)) .catch(err => console.error(err))

También puedes usar async y await para un código más legible: async function cargar() { try { const res = await fetch(https://fakestoreapi.com/products); const data = await res.json(); console.log(data); } catch(err) { console.error(err); } } cargar()

Axios

Axios es un cliente HTTP basado en promesas que simplifica las solicitudes asíncronas a APIs externas. Ofrece interceptores, cancelación de solicitudes, compatibilidad amplia con navegadores y manejo automático de JSON.

Uso típico: axios.get(https://api.ejemplo.com/items) .then(res => console.log(res.data)) .catch(err => console.error(err))

Si lo cargas por CDN, primero incluye el script en tu HTML y luego llama a axios.get hacia tu API, no hacia la URL del CDN.

Closures o cierres

Un closure es cuando una función interna recuerda y puede acceder a las variables de su función externa aunque esta ya haya finalizado. Esto permite encapsulación y estados privados.

Ejemplo funcional: function cuenta(monto) { let saldo = monto; return function retirar(importe) { saldo = saldo - importe; console.log(saldo); }; } const retirar1 = cuenta(1000); retirar1(50); const retirar2 = cuenta(500); retirar2(100)

Consejos rápidos

En fetch recuerda verificar res.ok antes de res.json para manejar errores HTTP. En Axios puedes configurar una instancia con baseURL y headers para reutilizar configuración. Los closures son útiles para crear módulos, contadores y control de acceso a datos internos.

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