Interview Q&A / Node.js
Node.js interview questions
The event loop on the server, streams, modules and building APIs with Express.
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- What is CORS and how do you enable it safely in an Express API?
CORS is a browser rule that blocks a page from reading responses from a different origin unless the server allows it with headers. In Express, use the cors package with an allow-list of origins, not a wildcard for private APIs.
IntermediateQuick answer1 min read - Where should a browser app store a JWT: localStorage or an httpOnly cookie?
An httpOnly, Secure, SameSite cookie keeps the token out of reach of JavaScript, so an XSS bug cannot steal it, but you must then handle CSRF. localStorage is simple but readable by any script on the page.
IntermediateQuick answer1 min read