Why it is an error to ignore a rejected promise on Chrome?

Question

I don't want to do anything if the promise is rejected, like getPromise().then(foo=>{});. Why is it an error on Chrome?

(new Promise((resolve, reject)=>{reject()}))
Promise {[[PromiseStatus]]: "rejected", [[PromiseValue]]: undefined}
VM3250:2 Uncaught (in promise) undefined

On Node and Firefox, it is OK to ignore the rejected part.

Answer 1

Rejecting a promise basically means something bad happened, and that you should be handling it with a call to catch. If you reject a promise without having a catch, it will throw an exception (more accurately, an unhandled rejection)

var a = (new Promise((resolve, reject) => {
    reject("my error")
})).catch((err) => {
    console.error(err)
})

I'm guessing it is a specificity of V8 if this happens only under Chrome, but it makes sense to me

Answer 2

Promise rejection is like uncaught exception. if you want to ignore exception - catch it, but don't handle, same here - add .catch statement, but do nothing

Promise.reject(new Error('bad..')).catch(e => {})

I would not however recommend that, as promises reject for a reason, so you might want to add some sort of handling logic