Deno's module loader currently strips a shebang if a module file
starts with one. However, this is no longer necessary, since there is
a stage-3 TC39 that adds support for shebangs (or "hashbangs") to the
language (https://github.com/tc39/proposal-hashbang), and V8, `tsc`
and `swc` all support it.
Furthermore, stripping shebangs causes a correctness bug with JSON
modules, since a JSON file with a shebang should not parse as a JSON
module, yet it does with this stripping. This change fixes this.
This commit adds proper support for import assertions and JSON modules.
Implementation of "core/modules.rs" was changed to account for multiple possible
module types, instead of always assuming that the code is an "ES module". In
effect "ModuleMap" now has knowledge about each modules' type (stored via
"ModuleType" enum). Module loading pipeline now stores information about
expected module type for each request and validates that expected type matches
discovered module type based on file's "MediaType".
Relevant tests were added to "core/modules.rs" and integration tests,
additionally multiple WPT tests were enabled.
There are still some rough edges in the implementation and not all WPT were
enabled, due to:
a) unclear BOM handling in source code by "FileFetcher"
b) design limitation of Deno's "FileFetcher" that doesn't download the same
module multiple times in a single run
Co-authored-by: Kitson Kelly <me@kitsonkelly.com>
