From b033f83da3b7eac2c188829cb10b7a4dc191a1ae Mon Sep 17 00:00:00 2001
From: Guy Bedford <guybedford@gmail.com>
Date: Sat, 28 Sep 2019 15:01:23 -0400
Subject: [PATCH 1/4] Revert "esm: remove experimental status from JSON
 modules"

This reverts commit ec8776da6fa77628e12718bb38cee687303d4137.
---
 doc/api/cli.md                              |  7 +++++++
 doc/api/esm.md                              | 19 ++++++++++++++++---
 doc/node.1                                  |  3 +++
 lib/internal/modules/esm/default_resolve.js |  7 +++++--
 src/node_options.cc                         |  8 ++++++++
 src/node_options.h                          |  1 +
 test/es-module/test-esm-json-cache.mjs      |  2 +-
 test/es-module/test-esm-json.mjs            |  3 +--
 8 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/doc/api/cli.md b/doc/api/cli.md
index c196adf038e646..3a16bbfe6dd2ec 100644
--- a/doc/api/cli.md
+++ b/doc/api/cli.md
@@ -156,6 +156,13 @@ added: v12.7.0
 
 Enable experimental resolution using the `exports` field in `package.json`.
 
+### `--experimental-json-modules`
+<!-- YAML
+added: v12.9.0
+-->
+
+Enable experimental JSON support for the ES Module loader.
+
 ### `--experimental-modules`
 <!-- YAML
 added: v8.5.0
diff --git a/doc/api/esm.md b/doc/api/esm.md
index 580528401629e2..329e5590ff973a 100644
--- a/doc/api/esm.md
+++ b/doc/api/esm.md
@@ -584,11 +584,16 @@ fs.readFileSync = () => Buffer.from('Hello, ESM');
 fs.readFileSync === readFileSync;
 ```
 
-## JSON Modules
+## Experimental JSON Modules
 
-JSON modules follow the [WHATWG JSON modules specification][].
+Currently importing JSON modules are only supported in the `commonjs` mode
+and are loaded using the CJS loader. [WHATWG JSON modules][] are currently
+being standardized, and are experimentally supported by including the
+additional flag `--experimental-json-modules` when running Node.js.
 
-The imported JSON only exposes a `default`. There is no
+When the `--experimental-json-modules` flag is included both the
+`commonjs` and `module` mode will use the new experimental JSON
+loader. The imported JSON only exposes a `default`, there is no
 support for named exports. A cache entry is created in the CommonJS
 cache, to avoid duplication. The same object will be returned in
 CommonJS if the JSON module has already been imported from the
@@ -601,6 +606,14 @@ Assuming an `index.mjs` with
 import packageConfig from './package.json';
 ```
 
+The `--experimental-json-modules` flag is needed for the module
+to work.
+
+```bash
+node --experimental-modules index.mjs # fails
+node --experimental-modules --experimental-json-modules index.mjs # works
+```
+
 ## Experimental Wasm Modules
 
 Importing Web Assembly modules is supported under the
diff --git a/doc/node.1 b/doc/node.1
index 2b7e3dc4292a48..7f786a05c6e51a 100644
--- a/doc/node.1
+++ b/doc/node.1
@@ -108,6 +108,9 @@ Requires Node.js to be built with
 .It Fl -es-module-specifier-resolution
 Select extension resolution algorithm for ES Modules; either 'explicit' (default) or 'node'
 .
+.It Fl -experimental-json-modules
+Enable experimental JSON interop support for the ES Module loader.
+.
 .It Fl -experimental-modules
 Enable experimental ES module support and caching modules.
 .
diff --git a/lib/internal/modules/esm/default_resolve.js b/lib/internal/modules/esm/default_resolve.js
index 580419deac6c05..7686e3e003eede 100644
--- a/lib/internal/modules/esm/default_resolve.js
+++ b/lib/internal/modules/esm/default_resolve.js
@@ -8,6 +8,7 @@ const { getOptionValue } = require('internal/options');
 
 const preserveSymlinks = getOptionValue('--preserve-symlinks');
 const preserveSymlinksMain = getOptionValue('--preserve-symlinks-main');
+const experimentalJsonModules = getOptionValue('--experimental-json-modules');
 const typeFlag = getOptionValue('--input-type');
 const experimentalWasmModules = getOptionValue('--experimental-wasm-modules');
 const { resolve: moduleWrapResolve,
@@ -28,7 +29,6 @@ const extensionFormatMap = {
   '__proto__': null,
   '.cjs': 'commonjs',
   '.js': 'module',
-  '.json': 'json',
   '.mjs': 'module'
 };
 
@@ -36,7 +36,7 @@ const legacyExtensionFormatMap = {
   '__proto__': null,
   '.cjs': 'commonjs',
   '.js': 'commonjs',
-  '.json': 'json',
+  '.json': 'commonjs',
   '.mjs': 'module',
   '.node': 'commonjs'
 };
@@ -44,6 +44,9 @@ const legacyExtensionFormatMap = {
 if (experimentalWasmModules)
   extensionFormatMap['.wasm'] = legacyExtensionFormatMap['.wasm'] = 'wasm';
 
+if (experimentalJsonModules)
+  extensionFormatMap['.json'] = legacyExtensionFormatMap['.json'] = 'json';
+
 function resolve(specifier, parentURL) {
   try {
     const parsed = new URL(specifier);
diff --git a/src/node_options.cc b/src/node_options.cc
index 34efe6336a08f2..e525f875dd0b22 100644
--- a/src/node_options.cc
+++ b/src/node_options.cc
@@ -135,6 +135,11 @@ void EnvironmentOptions::CheckOptions(std::vector<std::string>* errors) {
     }
   }
 
+  if (experimental_json_modules && !experimental_modules) {
+    errors->push_back("--experimental-json-modules requires "
+                      "--experimental-modules be enabled");
+  }
+
   if (experimental_wasm_modules && !experimental_modules) {
     errors->push_back("--experimental-wasm-modules requires "
                       "--experimental-modules be enabled");
@@ -311,6 +316,9 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
   AddOption("--experimental-exports",
             "experimental support for exports in package.json",
             &EnvironmentOptions::experimental_exports,
+  AddOption("--experimental-json-modules",
+            "experimental JSON interop support for the ES Module loader",
+            &EnvironmentOptions::experimental_json_modules,
             kAllowedInEnvironment);
   AddOption("--experimental-loader",
             "(with --experimental-modules) use the specified file as a "
diff --git a/src/node_options.h b/src/node_options.h
index 780e669eb6cd44..cc766dfd7b7ba7 100644
--- a/src/node_options.h
+++ b/src/node_options.h
@@ -101,6 +101,7 @@ class EnvironmentOptions : public Options {
  public:
   bool abort_on_uncaught_exception = false;
   bool experimental_exports = false;
+  bool experimental_json_modules = false;
   bool experimental_modules = false;
   std::string es_module_specifier_resolution;
   bool experimental_wasm_modules = false;
diff --git a/test/es-module/test-esm-json-cache.mjs b/test/es-module/test-esm-json-cache.mjs
index 0f7d6804061bcd..d1fee4f444c2c0 100644
--- a/test/es-module/test-esm-json-cache.mjs
+++ b/test/es-module/test-esm-json-cache.mjs
@@ -1,4 +1,4 @@
-// Flags: --experimental-modules
+// Flags: --experimental-modules --experimental-json-modules
 import '../common/index.mjs';
 
 import { strictEqual, deepStrictEqual } from 'assert';
diff --git a/test/es-module/test-esm-json.mjs b/test/es-module/test-esm-json.mjs
index f196945b4b68f4..3d246124a9bdae 100644
--- a/test/es-module/test-esm-json.mjs
+++ b/test/es-module/test-esm-json.mjs
@@ -1,5 +1,4 @@
-// Flags: --experimental-modules
-
+// Flags: --experimental-modules --experimental-json-modules
 import '../common/index.mjs';
 import { strictEqual } from 'assert';
 

From 5dc4167a4bce7a9bed0779df8630b4e46500abbd Mon Sep 17 00:00:00 2001
From: Guy Bedford <guybedford@gmail.com>
Date: Tue, 1 Oct 2019 00:03:50 -0400
Subject: [PATCH 2/4] fixup broken option

---
 src/node_options.cc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/node_options.cc b/src/node_options.cc
index e525f875dd0b22..ca4f97e8e889ed 100644
--- a/src/node_options.cc
+++ b/src/node_options.cc
@@ -316,6 +316,7 @@ EnvironmentOptionsParser::EnvironmentOptionsParser() {
   AddOption("--experimental-exports",
             "experimental support for exports in package.json",
             &EnvironmentOptions::experimental_exports,
+            kAllowedInEnvironment);
   AddOption("--experimental-json-modules",
             "experimental JSON interop support for the ES Module loader",
             &EnvironmentOptions::experimental_json_modules,

From 67d6171ada9fb4ca864d4b3b2e6572e1c59d89b0 Mon Sep 17 00:00:00 2001
From: Guy Bedford <guybedford@gmail.com>
Date: Tue, 1 Oct 2019 00:50:26 -0400
Subject: [PATCH 3/4] add to NODE_OPTIONS list

---
 doc/api/cli.md | 1 +
 1 file changed, 1 insertion(+)

diff --git a/doc/api/cli.md b/doc/api/cli.md
index 3a16bbfe6dd2ec..d58e287677b963 100644
--- a/doc/api/cli.md
+++ b/doc/api/cli.md
@@ -989,6 +989,7 @@ Node.js options that are allowed are:
 * `--enable-fips`
 * `--es-module-specifier-resolution`
 * `--experimental-exports`
+* `--experimental-json-modules`
 * `--experimental-loader`
 * `--experimental-modules`
 * `--experimental-policy`

From 7675c12a716469cf14c10fac997d22206880f632 Mon Sep 17 00:00:00 2001
From: Guy Bedford <guybedford@gmail.com>
Date: Tue, 1 Oct 2019 20:29:29 -0400
Subject: [PATCH 4/4] fixup doc spec link

---
 doc/api/esm.md | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/doc/api/esm.md b/doc/api/esm.md
index 329e5590ff973a..6fd0c510ef7490 100644
--- a/doc/api/esm.md
+++ b/doc/api/esm.md
@@ -587,8 +587,8 @@ fs.readFileSync === readFileSync;
 ## Experimental JSON Modules
 
 Currently importing JSON modules are only supported in the `commonjs` mode
-and are loaded using the CJS loader. [WHATWG JSON modules][] are currently
-being standardized, and are experimentally supported by including the
+and are loaded using the CJS loader. [WHATWG JSON modules specification][] are
+still being standardized, and are experimentally supported by including the
 additional flag `--experimental-json-modules` when running Node.js.
 
 When the `--experimental-json-modules` flag is included both the