FUTURE: remove import assertions support for JavaScript (#23541)

Ref #17944, https://github.com/swc-project/swc/issues/8893

TypeScript removes the `assert` keywords in the transpile, so this PR
only works for JavaScript files

14 files changed, 43 insertions, 20 deletions

diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index 1d8b06f49..b77a8afdb 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -110,7 +110,7 @@ pub static DENO_DISABLE_PEDANTIC_NODE_WARNINGS: Lazy<bool> = Lazy::new(|| {
     .is_some()
 });
 
-static DENO_FUTURE: Lazy<bool> =
+pub static DENO_FUTURE: Lazy<bool> =
   Lazy::new(|| std::env::var("DENO_FUTURE").ok().is_some());
 
 pub fn jsr_url() -> &'static Url {
diff --git a/cli/lsp/config.rs b/cli/lsp/config.rs
index 5ddc41cb2..e5703a21a 100644
--- a/cli/lsp/config.rs
+++ b/cli/lsp/config.rs
@@ -4,6 +4,7 @@ use super::logging::lsp_log;
 use crate::args::ConfigFile;
 use crate::args::FmtOptions;
 use crate::args::LintOptions;
+use crate::args::DENO_FUTURE;
 use crate::cache::FastInsecureHasher;
 use crate::file_fetcher::FileFetcher;
 use crate::lsp::logging::lsp_warn;
@@ -1324,7 +1325,7 @@ impl ConfigData {
         .as_ref()
         .map(|c| c.has_unstable("byonm"))
         .unwrap_or(false)
-      || (std::env::var("DENO_FUTURE").is_ok()
+      || (*DENO_FUTURE
         && package_json.is_some()
         && config_file
           .as_ref()
diff --git a/cli/main.rs b/cli/main.rs
index 142ae017c..3b103e780 100644
--- a/cli/main.rs
+++ b/cli/main.rs
@@ -29,6 +29,7 @@ mod worker;
 use crate::args::flags_from_vec;
 use crate::args::DenoSubcommand;
 use crate::args::Flags;
+use crate::args::DENO_FUTURE;
 use crate::util::display;
 use crate::util::v8::get_v8_flags_from_env;
 use crate::util::v8::init_v8_flags;
@@ -389,7 +390,15 @@ fn resolve_flags_and_init(
     // Using same default as VSCode:
     // https://github.com/microsoft/vscode/blob/48d4ba271686e8072fc6674137415bc80d936bc7/extensions/typescript-language-features/src/configuration/configuration.ts#L213-L214
     DenoSubcommand::Lsp => vec!["--max-old-space-size=3072".to_string()],
-    _ => vec![],
+    _ => {
+      if *DENO_FUTURE {
+        // deno_ast removes TypeScript `assert` keywords, so this flag only affects JavaScript
+        // TODO(petamoriken): Need to check TypeScript `assert` keywords in deno_ast
+        vec!["--no-harmony-import-assertions".to_string()]
+      } else {
+        vec![]
+      }
+    }
   };
 
   init_v8_flags(&default_v8_flags, &flags.v8_flags, get_v8_flags_from_env());
diff --git a/tests/integration/run_tests.rs b/tests/integration/run_tests.rs
index e28251b23..e92fd3627 100644
--- a/tests/integration/run_tests.rs
+++ b/tests/integration/run_tests.rs
@@ -1694,16 +1694,6 @@ fn type_directives_js_main() {
   assert_not_contains!(output.combined_output(), "type_reference.d.ts");
 }
 
-#[test]
-fn test_deno_futures_env() {
-  let context = TestContextBuilder::new().add_future_env_vars().build();
-  let output = context
-    .new_command()
-    .args("run --quiet --reload run/deno_futures_env.ts")
-    .run();
-  output.assert_exit_code(0);
-}
-
 itest!(type_directives_redirect {
   args: "run --reload --check run/type_directives_redirect.ts",
   output: "run/type_directives_redirect.ts.out",
diff --git a/tests/specs/future/import_assertions/__test__.jsonc b/tests/specs/future/import_assertions/__test__.jsonc
new file mode 100644
index 000000000..a1e759c75
--- /dev/null
+++ b/tests/specs/future/import_assertions/__test__.jsonc
@@ -0,0 +1,16 @@
+{
+  "steps": [
+    {
+      "args": "run main.js",
+      "output": "error.out",
+      "exitCode": 1,
+      "envs": {
+        "DENO_FUTURE": "1"
+      }
+    },
+    {
+      "args": "run main.js",
+      "output": "success.out"
+    }
+  ]
+}
diff --git a/tests/specs/future/import_assertions/error.out b/tests/specs/future/import_assertions/error.out
new file mode 100644
index 000000000..cef663f35
--- /dev/null
+++ b/tests/specs/future/import_assertions/error.out
@@ -0,0 +1,4 @@
+error: Uncaught SyntaxError: Unexpected identifier 'assert'
+import foo from "./main.json" assert { type: "json" };
+                              ^
+    at <anonymous> (file:///[WILDCARD]/main.js:[WILDCARD])
diff --git a/tests/specs/future/import_assertions/main.js b/tests/specs/future/import_assertions/main.js
new file mode 100644
index 000000000..9b4c4d036
--- /dev/null
+++ b/tests/specs/future/import_assertions/main.js
@@ -0,0 +1,2 @@
+import foo from "./main.json" assert { type: "json" };
+console.log(foo);
diff --git a/tests/specs/future/import_assertions/main.json b/tests/specs/future/import_assertions/main.json
new file mode 100644
index 000000000..abdd5202b
--- /dev/null
+++ b/tests/specs/future/import_assertions/main.json
@@ -0,0 +1,3 @@
+{
+  "foo": "foo"
+}
diff --git a/tests/specs/future/import_assertions/success.out b/tests/specs/future/import_assertions/success.out
new file mode 100644
index 000000000..70ec274d9
--- /dev/null
+++ b/tests/specs/future/import_assertions/success.out
@@ -0,0 +1 @@
+{ foo: "foo" }
diff --git a/tests/testdata/npm/import_json/main.js b/tests/testdata/npm/import_json/main.js
index b752bdef8..ac6cee9a8 100644
--- a/tests/testdata/npm/import_json/main.js
+++ b/tests/testdata/npm/import_json/main.js
@@ -1,4 +1,4 @@
-import json from "npm:@denotest/binary-package@1/package.json" assert {
+import json from "npm:@denotest/binary-package@1/package.json" with {
   type: "json",
 };
 console.log(json);
diff --git a/tests/testdata/run/deno_futures_env.ts b/tests/testdata/run/deno_futures_env.ts
deleted file mode 100644
index 21f76e367..000000000
--- a/tests/testdata/run/deno_futures_env.ts
+++ /dev/null
@@ -1,3 +0,0 @@
-if (typeof window !== "undefined") {
-  throw new Error("Window global available");
-}
diff --git a/tests/testdata/subdir/mod7.js b/tests/testdata/subdir/mod7.js
index 2bd4b5eb7..e71ced92e 100644
--- a/tests/testdata/subdir/mod7.js
+++ b/tests/testdata/subdir/mod7.js
@@ -1,3 +1,3 @@
-import json1 from "./json_1.json" assert { type: "json" };
+import json1 from "./json_1.json" with { type: "json" };
 
 console.log(json1);
diff --git a/tests/testdata/subdir/mod8.js b/tests/testdata/subdir/mod8.js
index 5bf7a49a8..ed41d992c 100644
--- a/tests/testdata/subdir/mod8.js
+++ b/tests/testdata/subdir/mod8.js
@@ -1,3 +1,3 @@
-import json3 from "./json_3.json" assert { type: "json" };
+import json3 from "./json_3.json" with { type: "json" };
 
 console.log(json3);
diff --git a/tools/napi/generate_symbols_lists.js b/tools/napi/generate_symbols_lists.js
index 96636ffd7..11cf1c434 100755
--- a/tools/napi/generate_symbols_lists.js
+++ b/tools/napi/generate_symbols_lists.js
@@ -1,7 +1,7 @@
 #!/usr/bin/env -S deno run --allow-read --allow-write
 // Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
 
-import exports from "../../cli/napi/sym/symbol_exports.json" assert {
+import exports from "../../cli/napi/sym/symbol_exports.json" with {
   type: "json",
 };