Ensuring the mangler doesn't try to mangle constructors

[fabiospampinato]

Mangling the following code:

class Foo {}

class Bar extends Foo {
  constructor () {
    super ();
  }
}

With this command:

esbuild '--mangle-props=.' ./foo.js

Generates this error:

✘ [ERROR] Unexpected "super"

    foo.js:5:4:
      5 │     super ();
        ╵     ~~~~~

IMO super calls in constructors should be automatically detected and ignored by the mangler.

[evanw]

Thanks for the report. It looks like this happens because --mangle-props=. causes constructor to be renamed to something else and then it's no longer a constructor. I will add a workaround for this.

For what it's worth I recommend not doing --mangle-props=. as you will have to manually add every single API you use as a reserved property or your code will be broken. I recommend instead using a common pattern for all properties you intend to be mangled that is unlikely to appear in the APIs you use (i.e. opt-in instead of opt-out). The reserved property setting is mainly intended as a last-resort override that may be necessary if code in a dependency you don't control happens to use a handful of names similar to the ones you want to use.

[fabiospampinato]

Thanks for the report. It looks like this happens because --mangle-props=. causes constructor to be renamed to something else and then it's no longer a constructor. I will add a workaround for this.

I see, now I understand the error message.

For what it's worth I recommend not doing --mangle-props=. as you will have to manually add every single API you use as a reserved property or your code will be broken. I recommend instead using a common pattern for all properties you intend to be mangled that is unlikely to appear in the APIs you use (i.e. opt-in instead of opt-out). The reserved property setting is mainly intended as a last-resort override that may be necessary if code in a dependency you don't control happens to use a handful of names similar to the ones you want to use.

I have a fairly narrow use case for this, a tiny library for which it's obvious what the public methods are and all of them are unit-tested, mangling everything except those methods seems like the best option for my use case, prefixing all the non-public stuff with _ or something would only make the code a bit uglier I think.