HowToCodePage

AJAX

Talking to a server without reloading the page.

💡
This course has 3 lessons. Start with the first one and use the next / previous links at the bottom of each lesson — the sidebar keeps the whole course in order.

Lessons

  1. Requests with fetchMake a request without reloading the page, read the response correctly, send data, and stop a slow request with AbortController.
  2. Bodies, headers and status codesWhich headers you control, how to read the response body, and how to branch on status codes without duplicating error handling everywhere.
  3. XMLHttpRequest and the gaps in fetchThe original transport API, upload progress with xhr.upload, and an honest comparison of when XMLHttpRequest is still the right tool.

More in Front-end Development

HTML CSS JavaScript TypeScript HTML DOM JSON Tailwind CSS Bootstrap 5 Foundation Vue.js React Next.js Angular jQuery ECharts Chart.js SVG Font Awesome

Last refreshed 2026-09-17.