Calling .finally via bracket notation

Question

Working with legacy code, I stumbled upon such code:

this.User.updateRole(params)
    .then(this._onUserDismissingSetSuccess(), this.$alert.error)
    ["finally"](function () {
        this.isSendingData = false;
    });

and some other occasions with ["finally"].

Which made me scratch my head: what's the deal, why not .finally()? Is it some pattern, some trick or what?

not sure, maybe some broken old browsers don't like `.finally` (doubt it though) I've seen similar shenanigans with `["catch"]` in the past - I think — Jaromanda X, May 29 '23 at 11:03
```Promise``` is an object, which means you can access it using ```Dot property accessor``` or ```Square brackets property accessor```. — Junius L, May 29 '23 at 11:07
Yeah, some linters (especially those that aren't handling es6+ code) I've found struggle to understand `.catch()` and `.finally()` as they think its part of a `try-catch-finally` — Nick Parsons, May 29 '23 at 11:16
@JaromandaX I've seen that many times in the company I'm working now. Full stack PHP programmers use PHP object property syntax a lot... Also saw this in the past jobs. In the previous job that were Python programmers... — Alexander Nenashev, May 29 '23 at 12:02
@JaromandaX Because `then` is not a reserved keyword, unlike `catch` or `finally`. — Bergi, May 29 '23 at 12:13

score 2 · Accepted Answer · answered May 29 '23 at 12:11

This must be really old code (or, code targeting really old browsers). Using keywords such as finally or catch with dot property access syntax was not supported in ES3. You had to quote these names in object literals and use bracket syntax when accessing these properties.

Calling .finally via bracket notation

1 Answers1