proposal-regexp-match-indices VS proposal-nullish-coalescing

For more info about this feature, you can refer to the official proposal repo.

It should be mentioned that this feature isn't part of the ECMAScript specification yet. It's currently a stage 3 proposal and will likely be part of ES2021 or ES2022.

RegExp Match Indices (?)

For more info about this feature, you can refer to the original proposal.

Propuesta

For comparison, here are the Javascript RFCs for the equivalent operators:

https://github.com/TC39/proposal-optional-chaining

https://github.com/tc39/proposal-nullish-coalescing

IMO optional chaining is a lifesaver when dealing with deeply nested JSON, and it's become indispensable in our Typescript code. But we also deal with JSON from various third-party endpoints in Python, and far too often we resort to an inefficient deep_get utility to make our code sensical.

> if json?.get("foo")?.get("bar")?[0]?.get("baz")

may seem messy but would be infinitely better than the fragile (note the nested list-of-a-single-dict, and how bugs can appear if it's not there):

> if json.get("foo", {}).get("bar", [{}])[0].get("baz")

or the inefficient

> if deep_get(json, "foo.bar.0.baz")

It's not nearly as good as the Typescript json.foo?.bar?.[0]?.baz - but it's good enough!

The nullish coalescing proposal provides a way to handle undefined or null values and provide default values for the expression. You can use the “??” operator to provide a default value for an expression.