Send asynchronous browser requests with fetch, XMLHttpRequest, JSON, errors, and progressive UI.
Lessons
Understand what AJAX is and why it updates pages without reloads.
AJAX Introduction is easiest to learn by reading the example, changing it, and observing the result.
async function loadLessons() {
const response = await fetch('/api/lessons', {
headers: { 'Accept': 'application/json' }
});
if (!response.ok) {
throw new Error(`HTTP ${response.status}`);
}
return response.json();
}
loadLessons()
.then(lessons => console.log(lessons))
.catch(error => console.error('Failed to load:', error.message));Practice the AJAX Introduction example in a small scratch file, then explain what changed and why.