Question 1

How does RSVP.js compare to native JavaScript promises?

Accepted Answer

RSVP.js is fully Promises/A+ compliant like native promises, but adds utilities like hash() and allSettled(), and ensures asynchronous consistency even for immediate values. However, for modern projects without legacy browser support, native promises might suffice without the extra dependency.

Question 2

Can I cancel a promise in RSVP.js?

Accepted Answer

No, RSVP.js does not support promise cancellation as it strictly adheres to the Promises/A+ specification, which doesn't include cancellation. For cancelable promises, you'd need to look at other libraries or implement custom abort logic.

Question 3

How to use RSVP.js with async/await syntax?

Accepted Answer

Since RSVP.js provides standard promise objects, you can use async/await directly if your environment supports ES2017+. Just await RSVP promises like native ones, but ensure you handle any polyfilling for older environments as needed.

Question 4

What are the instrumentation features in RSVP.js for debugging?

Accepted Answer

RSVP.js offers configurable event listeners for promise lifecycle events like 'created' or 'rejected', allowing you to track and debug asynchronous flows. You need to enable instrumentation via RSVP.configure('instrument', true) and can capture stacks for detailed analysis.

Question 5

Is RSVP.js still necessary with modern browsers?

Accepted Answer

For projects targeting only modern browsers with native promise support, RSVP.js might be unnecessary unless you need its specific utilities like hash() or TaskJS integration. It's more valuable for maintaining compatibility with older browsers like IE9+.

Question 6

How to handle multiple promises concurrently with RSVP.js?

Accepted Answer

Use RSVP.all() for arrays of promises to wait for all to fulfill, or RSVP.hash() for object literals. For cases where you want results even if some fail, use allSettled() or hashSettled(), which return states for each promise.

rsvp.js

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