Send asynchronous browser requests with fetch, XMLHttpRequest, JSON, errors, and progressive UI.
Lessons
Understand browser request security boundaries and credential handling.
CORS, CSRF and Credentials 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 CORS, CSRF and Credentials example in a small scratch file, then explain what changed and why.