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esm: use import attributes instead of import assertions
The old import assertions proposal has been renamed to "import attributes" with the follwing major changes: 1. The keyword is now `with` instead of `assert`. 2. Unknown assertions cause an error rather than being ignored, This commit updates the documentation to encourage folks to use the new syntax, and add aliases for module customization hooks. PR-URL: #50140 Backport-PR-URL: #51136 Fixes: #50134 Refs: v8/v8@159c82c Reviewed-By: Geoffrey Booth <[email protected]> Reviewed-By: Jacob Smith <[email protected]> Reviewed-By: Benjamin Gruenbaum <[email protected]>
1 parent c13969e commit a193be3

18 files changed

+68
-62
lines changed

‎.eslintrc.js‎

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@@ -44,10 +44,7 @@ module.exports = {
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parserOptions: {
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babelOptions: {
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plugins: [
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[
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Module._findPath('@babel/plugin-syntax-import-attributes'),
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{ deprecatedAssertSyntax: true },
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],
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Module._findPath('@babel/plugin-syntax-import-attributes'),
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],
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},
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requireConfigFile: false,

‎doc/api/esm.md‎

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@@ -7,6 +7,9 @@
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<!-- YAML
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added: v8.5.0
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changes:
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- version: REPLACEME
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pr-url: https://github.com/nodejs/node/pull/50140
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description: Add experimental support for import attributes.
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- version: v18.19.0
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pr-url: https://github.com/nodejs/node/pull/44710
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description: Module customization hooks are executed off the main thread.
@@ -202,7 +205,7 @@ added: v12.10.0
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```js
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import 'data:text/javascript,console.log("hello!");';
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import _ from 'data:application/json,"world!"' assert { type: 'json' };
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import _ from 'data:application/json,"world!"' with { type: 'json' };
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```
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`data:` URLs only resolve [bare specifiers][Terminology] for builtin modules
@@ -243,26 +246,25 @@ added:
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- v17.1.0
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- v16.14.0
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changes:
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- version: v18.19.0
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- version: REPLACEME
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pr-url: https://github.com/nodejs/node/pull/50140
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description: Switch from Import Assertions to Import Attributes.
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-->
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> Stability: 1.1 - Active development
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> This feature was previously named "Import assertions", and using the `assert`
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> keyword instead of `with`. Because the version of V8 on this release line does
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> not support the `with` keyword, you need to keep using `assert` to support
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> this version of Node.js.
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> keyword instead of `with`. Any uses in code of the prior `assert` keyword
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> should be updated to use `with` instead.
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The [Import Attributes proposal][] adds an inline syntax for module import
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statements to pass on more information alongside the module specifier.
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```js
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import fooData from './foo.json' assert { type: 'json' };
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import fooData from './foo.json' with { type: 'json' };
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const { default: barData } =
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await import('./bar.json', { assert: { type: 'json' } });
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await import('./bar.json', { with: { type: 'json' } });
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```
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Node.js supports the following `type` values, for which the attribute is
@@ -555,10 +557,10 @@ separate cache.
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JSON files can be referenced by `import`:
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```js
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import packageConfig from './package.json' assert { type: 'json' };
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import packageConfig from './package.json' with { type: 'json' };
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```
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The `assert { type: 'json' }` syntax is mandatory; see [Import Attributes][].
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The `with { type: 'json' }` syntax is mandatory; see [Import Attributes][].
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The imported JSON only exposes a `default` export. There is no support for named
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exports. A cache entry is created in the CommonJS cache to avoid duplication.

‎src/node.cc‎

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Original file line numberDiff line numberDiff line change
@@ -745,6 +745,13 @@ int ProcessGlobalArgs(std::vector<std::string>* args,
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"--no-harmony-import-assertions") == v8_args.end()) {
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v8_args.emplace_back("--harmony-import-assertions");
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}
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// TODO(aduh95): remove this when the harmony-import-attributes flag
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// is removed in V8.
750+
if (std::find(v8_args.begin(),
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v8_args.end(),
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"--no-harmony-import-attributes") == v8_args.end()) {
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v8_args.emplace_back("--harmony-import-attributes");
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}
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auto env_opts = per_process::cli_options->per_isolate->per_env;
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if (std::find(v8_args.begin(), v8_args.end(),

‎test/es-module/test-esm-assertionless-json-import.js‎

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@@ -9,7 +9,7 @@ async function test() {
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import('../fixtures/experimental.json'),
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import(
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'../fixtures/experimental.json',
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{ assert: { type: 'json' } }
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{ with: { type: 'json' } }
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),
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]);
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@@ -24,7 +24,7 @@ async function test() {
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import('../fixtures/experimental.json?test'),
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import(
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'../fixtures/experimental.json?test',
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{ assert: { type: 'json' } }
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{ with: { type: 'json' } }
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),
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]);
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@@ -39,7 +39,7 @@ async function test() {
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import('../fixtures/experimental.json#test'),
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import(
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'../fixtures/experimental.json#test',
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{ assert: { type: 'json' } }
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{ with: { type: 'json' } }
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),
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]);
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@@ -54,7 +54,7 @@ async function test() {
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import('../fixtures/experimental.json?test2#test'),
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import(
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'../fixtures/experimental.json?test2#test',
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{ assert: { type: 'json' } }
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{ with: { type: 'json' } }
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),
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]);
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@@ -69,7 +69,7 @@ async function test() {
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import('data:application/json,{"ofLife":42}'),
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import(
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'data:application/json,{"ofLife":42}',
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{ assert: { type: 'json' } }
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{ with: { type: 'json' } }
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),
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]);
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‎test/es-module/test-esm-data-urls.js‎

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@@ -60,36 +60,36 @@ function createBase64URL(mime, body) {
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}
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{
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const ns = await import('data:application/json;foo="test,"this"',
63-
{ assert: { type: 'json' } });
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{ with: { type: 'json' } });
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assert.deepStrictEqual(Object.keys(ns), ['default']);
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assert.strictEqual(ns.default, 'this');
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}
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{
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const ns = await import(`data:application/json;foo=${
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encodeURIComponent('test,')
70-
},0`, { assert: { type: 'json' } });
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},0`, { with: { type: 'json' } });
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assert.deepStrictEqual(Object.keys(ns), ['default']);
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assert.strictEqual(ns.default, 0);
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}
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{
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await assert.rejects(async () =>
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import('data:application/json;foo="test,",0',
77-
{ assert: { type: 'json' } }), {
77+
{ with: { type: 'json' } }), {
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name: 'SyntaxError',
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message: /Unexpected end of JSON input/
8080
});
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}
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{
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const body = '{"x": 1}';
8484
const plainESMURL = createURL('application/json', body);
85-
const ns = await import(plainESMURL, { assert: { type: 'json' } });
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const ns = await import(plainESMURL, { with: { type: 'json' } });
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assert.deepStrictEqual(Object.keys(ns), ['default']);
8787
assert.strictEqual(ns.default.x, 1);
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}
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{
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const body = '{"default": 2}';
9191
const plainESMURL = createURL('application/json', body);
92-
const ns = await import(plainESMURL, { assert: { type: 'json' } });
92+
const ns = await import(plainESMURL, { with: { type: 'json' } });
9393
assert.deepStrictEqual(Object.keys(ns), ['default']);
9494
assert.strictEqual(ns.default.default, 2);
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}

‎test/es-module/test-esm-dynamic-import-attribute.js‎

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Original file line numberDiff line numberDiff line change
@@ -5,7 +5,7 @@ const { strictEqual } = require('assert');
55
async function test() {
66
{
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const results = await Promise.allSettled([
8-
import('../fixtures/empty.js', { assert: { type: 'json' } }),
8+
import('../fixtures/empty.js', { with: { type: 'json' } }),
99
import('../fixtures/empty.js'),
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]);
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@@ -16,7 +16,7 @@ async function test() {
1616
{
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const results = await Promise.allSettled([
1818
import('../fixtures/empty.js'),
19-
import('../fixtures/empty.js', { assert: { type: 'json' } }),
19+
import('../fixtures/empty.js', { with: { type: 'json' } }),
2020
]);
2121

2222
strictEqual(results[0].status, 'fulfilled');
@@ -25,7 +25,7 @@ async function test() {
2525

2626
{
2727
const results = await Promise.allSettled([
28-
import('../fixtures/empty.json', { assert: { type: 'json' } }),
28+
import('../fixtures/empty.json', { with: { type: 'json' } }),
2929
import('../fixtures/empty.json'),
3030
]);
3131

@@ -36,7 +36,7 @@ async function test() {
3636
{
3737
const results = await Promise.allSettled([
3838
import('../fixtures/empty.json'),
39-
import('../fixtures/empty.json', { assert: { type: 'json' } }),
39+
import('../fixtures/empty.json', { with: { type: 'json' } }),
4040
]);
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4242
strictEqual(results[0].status, 'rejected');

‎test/es-module/test-esm-dynamic-import-attribute.mjs‎

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@@ -3,7 +3,7 @@ import { strictEqual } from 'assert';
33

44
{
55
const results = await Promise.allSettled([
6-
import('../fixtures/empty.js', { assert: { type: 'json' } }),
6+
import('../fixtures/empty.js', { with: { type: 'json' } }),
77
import('../fixtures/empty.js'),
88
]);
99

@@ -14,7 +14,7 @@ import { strictEqual } from 'assert';
1414
{
1515
const results = await Promise.allSettled([
1616
import('../fixtures/empty.js'),
17-
import('../fixtures/empty.js', { assert: { type: 'json' } }),
17+
import('../fixtures/empty.js', { with: { type: 'json' } }),
1818
]);
1919

2020
strictEqual(results[0].status, 'fulfilled');
@@ -23,7 +23,7 @@ import { strictEqual } from 'assert';
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2424
{
2525
const results = await Promise.allSettled([
26-
import('../fixtures/empty.json', { assert: { type: 'json' } }),
26+
import('../fixtures/empty.json', { with: { type: 'json' } }),
2727
import('../fixtures/empty.json'),
2828
]);
2929

@@ -34,7 +34,7 @@ import { strictEqual } from 'assert';
3434
{
3535
const results = await Promise.allSettled([
3636
import('../fixtures/empty.json'),
37-
import('../fixtures/empty.json', { assert: { type: 'json' } }),
37+
import('../fixtures/empty.json', { with: { type: 'json' } }),
3838
]);
3939

4040
strictEqual(results[0].status, 'rejected');

‎test/es-module/test-esm-import-attributes-1.mjs‎

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Original file line numberDiff line numberDiff line change
@@ -1,6 +1,6 @@
11
import '../common/index.mjs';
22
import { strictEqual } from 'assert';
33

4-
import secret from '../fixtures/experimental.json' assert { type: 'json' };
4+
import secret from '../fixtures/experimental.json' with { type: 'json' };
55

66
strictEqual(secret.ofLife, 42);

‎test/es-module/test-esm-import-attributes-2.mjs‎

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Original file line numberDiff line numberDiff line change
@@ -1,9 +1,9 @@
11
import '../common/index.mjs';
22
import { strictEqual } from 'assert';
33

4-
import secret0 from '../fixtures/experimental.json' assert { type: 'json' };
4+
import secret0 from '../fixtures/experimental.json' with { type: 'json' };
55
const secret1 = await import('../fixtures/experimental.json', {
6-
assert: { type: 'json' },
6+
with: { type: 'json' },
77
});
88

99
strictEqual(secret0.ofLife, 42);

‎test/es-module/test-esm-import-attributes-3.mjs‎

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@@ -1,9 +1,9 @@
11
import '../common/index.mjs';
22
import { strictEqual } from 'assert';
33

4-
import secret0 from '../fixtures/experimental.json' assert { type: 'json' };
4+
import secret0 from '../fixtures/experimental.json' with { type: 'json' };
55
const secret1 = await import('../fixtures/experimental.json',
6-
{ assert: { type: 'json' } });
6+
{ with: { type: 'json' } });
77

88
strictEqual(secret0.ofLife, 42);
99
strictEqual(secret1.default.ofLife, 42);

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