From d2c1e0eb02feb74ccef3dc2d01f173996a40e2bf Mon Sep 17 00:00:00 2001
From: bluwy <bjornlu.dev@gmail.com>
Date: Mon, 11 Oct 2021 23:45:40 +0800
Subject: [PATCH 1/8] feat: add enableSourcemap option

---
 src/compiler/compile/Component.ts        | 29 +++++++++++++++---------
 src/compiler/compile/index.ts            |  3 ++-
 src/compiler/compile/render_dom/index.ts | 12 +++++++---
 src/compiler/compile/render_ssr/index.ts |  4 +++-
 src/compiler/interfaces.ts               |  1 +
 5 files changed, 33 insertions(+), 16 deletions(-)

diff --git a/src/compiler/compile/Component.ts b/src/compiler/compile/Component.ts
index 202e14fd9813..346c1a869b86 100644
--- a/src/compiler/compile/Component.ts
+++ b/src/compiler/compile/Component.ts
@@ -342,22 +342,29 @@ export default class Component {
 			css = compile_options.customElement
 				? { code: null, map: null }
 				: result.css;
+				
+			const jsSourcemapEnabled = compile_options.enableSourcemap === true || compile_options.enableSourcemap === 'js'
 
-			const sourcemap_source_filename = get_sourcemap_source_filename(compile_options);
+			if (!jsSourcemapEnabled) {
+				js = print(program);
+				js.map = null;
+			} else {
+				const sourcemap_source_filename = get_sourcemap_source_filename(compile_options);
 
-			js = print(program, {
-				sourceMapSource: sourcemap_source_filename
-			});
+				js = print(program, {
+					sourceMapSource: sourcemap_source_filename,
+				});
 
-			js.map.sources = [
-				sourcemap_source_filename
-			];
+				js.map.sources = [
+					sourcemap_source_filename
+				];
 
-			js.map.sourcesContent = [
-				this.source
-			];
+				js.map.sourcesContent = [
+					this.source
+				];
 
-			js.map = apply_preprocessor_sourcemap(sourcemap_source_filename, js.map, compile_options.sourcemap as (string | RawSourceMap | DecodedSourceMap));
+				js.map = apply_preprocessor_sourcemap(sourcemap_source_filename, js.map, compile_options.sourcemap as (string | RawSourceMap | DecodedSourceMap));
+			}
 		}
 
 		return {
diff --git a/src/compiler/compile/index.ts b/src/compiler/compile/index.ts
index 96b24bceeed8..afe9c56cf4ca 100644
--- a/src/compiler/compile/index.ts
+++ b/src/compiler/compile/index.ts
@@ -13,6 +13,7 @@ const valid_options = [
 	'name',
 	'filename',
 	'sourcemap',
+	'enableSourcemap',
 	'generate',
 	'errorMode',
 	'varsReport',
@@ -82,7 +83,7 @@ function validate_options(options: CompileOptions, warnings: Warning[]) {
 }
 
 export default function compile(source: string, options: CompileOptions = {}) {
-	options = Object.assign({ generate: 'dom', dev: false }, options);
+	options = Object.assign({ generate: 'dom', dev: false, enableSourcemap: true }, options);
 
 	const stats = new Stats();
 	const warnings = [];
diff --git a/src/compiler/compile/render_dom/index.ts b/src/compiler/compile/render_dom/index.ts
index f74f4cdf1ccb..26f9ad9de3c1 100644
--- a/src/compiler/compile/render_dom/index.ts
+++ b/src/compiler/compile/render_dom/index.ts
@@ -33,10 +33,16 @@ export default function dom(
 	}
 
 	const css = component.stylesheet.render(options.filename, !options.customElement);
+	
+	const cssSourcemapEnabled = options.enableSourcemap === true || options.enableSourcemap === 'css';
 
-	css.map = apply_preprocessor_sourcemap(options.filename, css.map, options.sourcemap as string | RawSourceMap | DecodedSourceMap);
+	if (cssSourcemapEnabled) {
+		css.map = apply_preprocessor_sourcemap(options.filename, css.map, options.sourcemap as string | RawSourceMap | DecodedSourceMap);
+	} else {
+		css.map = null;
+	}
 
-	const styles = component.stylesheet.has_styles && options.dev
+	const styles = cssSourcemapEnabled && component.stylesheet.has_styles && options.dev
 		? `${css.code}\n/*# sourceMappingURL=${css.map.toUrl()} */`
 		: css.code;
 
@@ -521,7 +527,7 @@ export default function dom(
 				constructor(options) {
 					super();
 
-					${css.code && b`this.shadowRoot.innerHTML = \`<style>${css.code.replace(/\\/g, '\\\\')}${options.dev ? `\n/*# sourceMappingURL=${css.map.toUrl()} */` : ''}</style>\`;`}
+					${css.code && b`this.shadowRoot.innerHTML = \`<style>${css.code.replace(/\\/g, '\\\\')}${cssSourcemapEnabled && options.dev ? `\n/*# sourceMappingURL=${css.map.toUrl()} */` : ''}</style>\`;`}
 
 					@init(this, { target: this.shadowRoot, props: ${init_props}, customElement: true }, ${definition}, ${has_create_fragment ? 'create_fragment' : 'null'}, ${not_equal}, ${prop_indexes}, null, ${dirty});
 
diff --git a/src/compiler/compile/render_ssr/index.ts b/src/compiler/compile/render_ssr/index.ts
index b35a6ce6ffee..e7ee9dfe5e8e 100644
--- a/src/compiler/compile/render_ssr/index.ts
+++ b/src/compiler/compile/render_ssr/index.ts
@@ -200,11 +200,13 @@ export default function ssr(
 		main
 	].filter(Boolean);
 
+	const cssSourcemapEnabled = options.enableSourcemap === true || options.enableSourcemap === 'css';
+	
 	const js = b`
 		${css.code ? b`
 		const #css = {
 			code: "${css.code}",
-			map: ${css.map ? string_literal(css.map.toString()) : 'null'}
+			map: ${cssSourcemapEnabled && css.map ? string_literal(css.map.toString()) : 'null'}
 		};` : null}
 
 		${component.extract_javascript(component.ast.module)}
diff --git a/src/compiler/interfaces.ts b/src/compiler/interfaces.ts
index 7446c4c14b57..3b2f93278e76 100644
--- a/src/compiler/interfaces.ts
+++ b/src/compiler/interfaces.ts
@@ -147,6 +147,7 @@ export interface CompileOptions {
 	varsReport?: 'full' | 'strict' | false;
 
 	sourcemap?: object | string;
+	enableSourcemap?: boolean | 'js' | 'css';
 	outputFilename?: string;
 	cssOutputFilename?: string;
 	sveltePath?: string;

From 35d4fd7e33876d5a4b0293e116658bbb91880d6e Mon Sep 17 00:00:00 2001
From: bluwy <bjornlu.dev@gmail.com>
Date: Mon, 11 Oct 2021 23:45:57 +0800
Subject: [PATCH 2/8] chore: add tests

---
 test/sourcemaps/index.ts                             | 12 +++++++-----
 test/sourcemaps/samples/no-sourcemap/_config.js      |  5 +++++
 test/sourcemaps/samples/no-sourcemap/input.svelte    | 11 +++++++++++
 test/sourcemaps/samples/no-sourcemap/test.js         |  4 ++++
 .../sourcemaps/samples/only-css-sourcemap/_config.js |  5 +++++
 .../samples/only-css-sourcemap/input.svelte          | 11 +++++++++++
 test/sourcemaps/samples/only-css-sourcemap/test.js   |  4 ++++
 test/sourcemaps/samples/only-js-sourcemap/_config.js |  5 +++++
 .../samples/only-js-sourcemap/input.svelte           | 11 +++++++++++
 test/sourcemaps/samples/only-js-sourcemap/test.js    |  4 ++++
 10 files changed, 67 insertions(+), 5 deletions(-)
 create mode 100644 test/sourcemaps/samples/no-sourcemap/_config.js
 create mode 100644 test/sourcemaps/samples/no-sourcemap/input.svelte
 create mode 100644 test/sourcemaps/samples/no-sourcemap/test.js
 create mode 100644 test/sourcemaps/samples/only-css-sourcemap/_config.js
 create mode 100644 test/sourcemaps/samples/only-css-sourcemap/input.svelte
 create mode 100644 test/sourcemaps/samples/only-css-sourcemap/test.js
 create mode 100644 test/sourcemaps/samples/only-js-sourcemap/_config.js
 create mode 100644 test/sourcemaps/samples/only-js-sourcemap/input.svelte
 create mode 100644 test/sourcemaps/samples/only-js-sourcemap/test.js

diff --git a/test/sourcemaps/index.ts b/test/sourcemaps/index.ts
index 903629c06b1b..fc021cd6a7ca 100644
--- a/test/sourcemaps/index.ts
+++ b/test/sourcemaps/index.ts
@@ -85,11 +85,13 @@ describe('sourcemaps', () => {
 				);
 			}
 
-			assert.deepEqual(
-				js.map.sources.slice().sort(),
-				(config.js_map_sources || ['input.svelte']).sort(),
-				'js.map.sources is wrong'
-			);
+			if (js.map) {
+				assert.deepEqual(
+					js.map.sources.slice().sort(),
+					(config.js_map_sources || ['input.svelte']).sort(),
+					'js.map.sources is wrong'
+				);
+			}
 			if (css.map) {
 				assert.deepEqual(
 					css.map.sources.slice().sort(),
diff --git a/test/sourcemaps/samples/no-sourcemap/_config.js b/test/sourcemaps/samples/no-sourcemap/_config.js
new file mode 100644
index 000000000000..5b84d4055408
--- /dev/null
+++ b/test/sourcemaps/samples/no-sourcemap/_config.js
@@ -0,0 +1,5 @@
+export default {
+  compile_options: {
+    enableSourcemap: false
+  }
+};
diff --git a/test/sourcemaps/samples/no-sourcemap/input.svelte b/test/sourcemaps/samples/no-sourcemap/input.svelte
new file mode 100644
index 000000000000..91a483c9aa37
--- /dev/null
+++ b/test/sourcemaps/samples/no-sourcemap/input.svelte
@@ -0,0 +1,11 @@
+<script>
+	export let foo;
+</script>
+
+<p>{foo}</p>
+
+<style>
+	p {
+		color: red;
+	}
+</style>
\ No newline at end of file
diff --git a/test/sourcemaps/samples/no-sourcemap/test.js b/test/sourcemaps/samples/no-sourcemap/test.js
new file mode 100644
index 000000000000..127459a54e6e
--- /dev/null
+++ b/test/sourcemaps/samples/no-sourcemap/test.js
@@ -0,0 +1,4 @@
+export function test({ assert, js, css }) {
+	assert.equal(js.map, null);
+	assert.equal(css.map, null);
+}
diff --git a/test/sourcemaps/samples/only-css-sourcemap/_config.js b/test/sourcemaps/samples/only-css-sourcemap/_config.js
new file mode 100644
index 000000000000..011ea33f9193
--- /dev/null
+++ b/test/sourcemaps/samples/only-css-sourcemap/_config.js
@@ -0,0 +1,5 @@
+export default {
+  compile_options: {
+    enableSourcemap: 'css'
+  }
+};
diff --git a/test/sourcemaps/samples/only-css-sourcemap/input.svelte b/test/sourcemaps/samples/only-css-sourcemap/input.svelte
new file mode 100644
index 000000000000..91a483c9aa37
--- /dev/null
+++ b/test/sourcemaps/samples/only-css-sourcemap/input.svelte
@@ -0,0 +1,11 @@
+<script>
+	export let foo;
+</script>
+
+<p>{foo}</p>
+
+<style>
+	p {
+		color: red;
+	}
+</style>
\ No newline at end of file
diff --git a/test/sourcemaps/samples/only-css-sourcemap/test.js b/test/sourcemaps/samples/only-css-sourcemap/test.js
new file mode 100644
index 000000000000..a7ac6a9b0bdd
--- /dev/null
+++ b/test/sourcemaps/samples/only-css-sourcemap/test.js
@@ -0,0 +1,4 @@
+export function test({ assert, js, css }) {
+	assert.equal(js.map, null);
+	assert.notEqual(css.map, null);
+}
diff --git a/test/sourcemaps/samples/only-js-sourcemap/_config.js b/test/sourcemaps/samples/only-js-sourcemap/_config.js
new file mode 100644
index 000000000000..9a5bd733a1b5
--- /dev/null
+++ b/test/sourcemaps/samples/only-js-sourcemap/_config.js
@@ -0,0 +1,5 @@
+export default {
+  compile_options: {
+    enableSourcemap: 'js'
+  }
+};
diff --git a/test/sourcemaps/samples/only-js-sourcemap/input.svelte b/test/sourcemaps/samples/only-js-sourcemap/input.svelte
new file mode 100644
index 000000000000..91a483c9aa37
--- /dev/null
+++ b/test/sourcemaps/samples/only-js-sourcemap/input.svelte
@@ -0,0 +1,11 @@
+<script>
+	export let foo;
+</script>
+
+<p>{foo}</p>
+
+<style>
+	p {
+		color: red;
+	}
+</style>
\ No newline at end of file
diff --git a/test/sourcemaps/samples/only-js-sourcemap/test.js b/test/sourcemaps/samples/only-js-sourcemap/test.js
new file mode 100644
index 000000000000..b150653c3d72
--- /dev/null
+++ b/test/sourcemaps/samples/only-js-sourcemap/test.js
@@ -0,0 +1,4 @@
+export function test({ assert, js, css }) {
+	assert.notEqual(js.map, null);
+	assert.equal(css.map, null);
+}

From 5c4d77d939b704df4aa20748b540ad414f6a2c00 Mon Sep 17 00:00:00 2001
From: bluwy <bjornlu.dev@gmail.com>
Date: Mon, 11 Oct 2021 23:55:50 +0800
Subject: [PATCH 3/8] chore: add docs

---
 site/content/docs/04-compile-time.md | 1 +
 src/compiler/compile/Component.ts    | 4 ++--
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/site/content/docs/04-compile-time.md b/site/content/docs/04-compile-time.md
index ed6977f81fc8..3dd59244ccc8 100644
--- a/site/content/docs/04-compile-time.md
+++ b/site/content/docs/04-compile-time.md
@@ -82,6 +82,7 @@ The following options can be passed to the compiler. None are required:
 | `loopGuardTimeout` | 0 | A `number` that tells Svelte to break the loop if it blocks the thread for more than `loopGuardTimeout` ms. This is useful to prevent infinite loops. **Only available when `dev: true`**
 | `preserveComments` | `false` | If `true`, your HTML comments will be preserved during server-side rendering. By default, they are stripped out.
 | `preserveWhitespace` | `false` | If `true`, whitespace inside and between elements is kept as you typed it, rather than removed or collapsed to a single space where possible.
+| `enableSourcemap` | `boolean | 'js' | 'css'` | If `true`, Svelte generate sourcemaps for components. Use `js` or `css` for more granular control of sourcemap generation. By default, this is `true`.
 | `outputFilename` | `null` | A `string` used for your JavaScript sourcemap.
 | `cssOutputFilename` | `null` | A `string` used for your CSS sourcemap.
 | `sveltePath` | `"svelte"` | The location of the `svelte` package. Any imports from `svelte` or `svelte/[module]` will be modified accordingly.
diff --git a/src/compiler/compile/Component.ts b/src/compiler/compile/Component.ts
index 346c1a869b86..885c3391e41e 100644
--- a/src/compiler/compile/Component.ts
+++ b/src/compiler/compile/Component.ts
@@ -343,7 +343,7 @@ export default class Component {
 				? { code: null, map: null }
 				: result.css;
 				
-			const jsSourcemapEnabled = compile_options.enableSourcemap === true || compile_options.enableSourcemap === 'js'
+			const jsSourcemapEnabled = compile_options.enableSourcemap === true || compile_options.enableSourcemap === 'js';
 
 			if (!jsSourcemapEnabled) {
 				js = print(program);
@@ -352,7 +352,7 @@ export default class Component {
 				const sourcemap_source_filename = get_sourcemap_source_filename(compile_options);
 
 				js = print(program, {
-					sourceMapSource: sourcemap_source_filename,
+					sourceMapSource: sourcemap_source_filename
 				});
 
 				js.map.sources = [

From 8a7ce000c0dcfb8e96e5f57c9ba536ba90f2ec6a Mon Sep 17 00:00:00 2001
From: bluwy <bjornlu.dev@gmail.com>
Date: Wed, 13 Oct 2021 00:25:19 +0800
Subject: [PATCH 4/8] chore: apply pr suggestions

---
 site/content/docs/04-compile-time.md                    | 1 +
 test/sourcemaps/samples/no-sourcemap/input.svelte       | 2 +-
 test/sourcemaps/samples/only-css-sourcemap/input.svelte | 2 +-
 test/sourcemaps/samples/only-js-sourcemap/input.svelte  | 2 +-
 4 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/site/content/docs/04-compile-time.md b/site/content/docs/04-compile-time.md
index 3dd59244ccc8..2848cfb7f499 100644
--- a/site/content/docs/04-compile-time.md
+++ b/site/content/docs/04-compile-time.md
@@ -82,6 +82,7 @@ The following options can be passed to the compiler. None are required:
 | `loopGuardTimeout` | 0 | A `number` that tells Svelte to break the loop if it blocks the thread for more than `loopGuardTimeout` ms. This is useful to prevent infinite loops. **Only available when `dev: true`**
 | `preserveComments` | `false` | If `true`, your HTML comments will be preserved during server-side rendering. By default, they are stripped out.
 | `preserveWhitespace` | `false` | If `true`, whitespace inside and between elements is kept as you typed it, rather than removed or collapsed to a single space where possible.
+| `sourcemap` | `object | string` | An initial sourcemap that will be merged into the final output sourcemap.
 | `enableSourcemap` | `boolean | 'js' | 'css'` | If `true`, Svelte generate sourcemaps for components. Use `js` or `css` for more granular control of sourcemap generation. By default, this is `true`.
 | `outputFilename` | `null` | A `string` used for your JavaScript sourcemap.
 | `cssOutputFilename` | `null` | A `string` used for your CSS sourcemap.
diff --git a/test/sourcemaps/samples/no-sourcemap/input.svelte b/test/sourcemaps/samples/no-sourcemap/input.svelte
index 91a483c9aa37..6d39eaad0e79 100644
--- a/test/sourcemaps/samples/no-sourcemap/input.svelte
+++ b/test/sourcemaps/samples/no-sourcemap/input.svelte
@@ -8,4 +8,4 @@
 	p {
 		color: red;
 	}
-</style>
\ No newline at end of file
+</style>
diff --git a/test/sourcemaps/samples/only-css-sourcemap/input.svelte b/test/sourcemaps/samples/only-css-sourcemap/input.svelte
index 91a483c9aa37..6d39eaad0e79 100644
--- a/test/sourcemaps/samples/only-css-sourcemap/input.svelte
+++ b/test/sourcemaps/samples/only-css-sourcemap/input.svelte
@@ -8,4 +8,4 @@
 	p {
 		color: red;
 	}
-</style>
\ No newline at end of file
+</style>
diff --git a/test/sourcemaps/samples/only-js-sourcemap/input.svelte b/test/sourcemaps/samples/only-js-sourcemap/input.svelte
index 91a483c9aa37..6d39eaad0e79 100644
--- a/test/sourcemaps/samples/only-js-sourcemap/input.svelte
+++ b/test/sourcemaps/samples/only-js-sourcemap/input.svelte
@@ -8,4 +8,4 @@
 	p {
 		color: red;
 	}
-</style>
\ No newline at end of file
+</style>

From 81b0ddf157d9671018c7b787ef0c1dd6a65d9c60 Mon Sep 17 00:00:00 2001
From: bluwy <bjornlu.dev@gmail.com>
Date: Wed, 13 Oct 2021 00:31:32 +0800
Subject: [PATCH 5/8] docs: further explain sourcemap

---
 site/content/docs/04-compile-time.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/site/content/docs/04-compile-time.md b/site/content/docs/04-compile-time.md
index 2848cfb7f499..9459829edfae 100644
--- a/site/content/docs/04-compile-time.md
+++ b/site/content/docs/04-compile-time.md
@@ -82,7 +82,7 @@ The following options can be passed to the compiler. None are required:
 | `loopGuardTimeout` | 0 | A `number` that tells Svelte to break the loop if it blocks the thread for more than `loopGuardTimeout` ms. This is useful to prevent infinite loops. **Only available when `dev: true`**
 | `preserveComments` | `false` | If `true`, your HTML comments will be preserved during server-side rendering. By default, they are stripped out.
 | `preserveWhitespace` | `false` | If `true`, whitespace inside and between elements is kept as you typed it, rather than removed or collapsed to a single space where possible.
-| `sourcemap` | `object | string` | An initial sourcemap that will be merged into the final output sourcemap.
+| `sourcemap` | `object | string` | An initial sourcemap that will be merged into the final output sourcemap. Usually assigned with the preprocess sourcemap.
 | `enableSourcemap` | `boolean | 'js' | 'css'` | If `true`, Svelte generate sourcemaps for components. Use `js` or `css` for more granular control of sourcemap generation. By default, this is `true`.
 | `outputFilename` | `null` | A `string` used for your JavaScript sourcemap.
 | `cssOutputFilename` | `null` | A `string` used for your CSS sourcemap.

From 797818dc1573f2f271d2bb8b50362f80479d1329 Mon Sep 17 00:00:00 2001
From: Bjorn Lu <34116392+bluwy@users.noreply.github.com>
Date: Wed, 13 Oct 2021 01:20:28 +0800
Subject: [PATCH 6/8] Update site/content/docs/04-compile-time.md

Co-authored-by: Ben McCann <322311+benmccann@users.noreply.github.com>
---
 site/content/docs/04-compile-time.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/site/content/docs/04-compile-time.md b/site/content/docs/04-compile-time.md
index 9459829edfae..948cf1713ec7 100644
--- a/site/content/docs/04-compile-time.md
+++ b/site/content/docs/04-compile-time.md
@@ -82,7 +82,7 @@ The following options can be passed to the compiler. None are required:
 | `loopGuardTimeout` | 0 | A `number` that tells Svelte to break the loop if it blocks the thread for more than `loopGuardTimeout` ms. This is useful to prevent infinite loops. **Only available when `dev: true`**
 | `preserveComments` | `false` | If `true`, your HTML comments will be preserved during server-side rendering. By default, they are stripped out.
 | `preserveWhitespace` | `false` | If `true`, whitespace inside and between elements is kept as you typed it, rather than removed or collapsed to a single space where possible.
-| `sourcemap` | `object | string` | An initial sourcemap that will be merged into the final output sourcemap. Usually assigned with the preprocess sourcemap.
+| `sourcemap` | `object | string` | An initial sourcemap that will be merged into the final output sourcemap. This is usually the preprocessor sourcemap.
 | `enableSourcemap` | `boolean | 'js' | 'css'` | If `true`, Svelte generate sourcemaps for components. Use `js` or `css` for more granular control of sourcemap generation. By default, this is `true`.
 | `outputFilename` | `null` | A `string` used for your JavaScript sourcemap.
 | `cssOutputFilename` | `null` | A `string` used for your CSS sourcemap.

From ea2854ae7395c67ad4ee3e2c242713b4baee2e3e Mon Sep 17 00:00:00 2001
From: bluwy <bjornlu.dev@gmail.com>
Date: Wed, 13 Oct 2021 11:35:28 +0800
Subject: [PATCH 7/8] fix: use object type

---
 site/content/docs/04-compile-time.md                  |  2 +-
 src/compiler/compile/Component.ts                     |  3 ++-
 src/compiler/compile/render_dom/index.ts              |  3 ++-
 src/compiler/compile/render_ssr/index.ts              |  3 ++-
 src/compiler/compile/utils/check_enable_sourcemap.ts  | 10 ++++++++++
 src/compiler/interfaces.ts                            |  4 +++-
 test/sourcemaps/samples/only-css-sourcemap/_config.js |  2 +-
 test/sourcemaps/samples/only-js-sourcemap/_config.js  |  2 +-
 8 files changed, 22 insertions(+), 7 deletions(-)
 create mode 100644 src/compiler/compile/utils/check_enable_sourcemap.ts

diff --git a/site/content/docs/04-compile-time.md b/site/content/docs/04-compile-time.md
index 948cf1713ec7..8e709d7c37cc 100644
--- a/site/content/docs/04-compile-time.md
+++ b/site/content/docs/04-compile-time.md
@@ -83,7 +83,7 @@ The following options can be passed to the compiler. None are required:
 | `preserveComments` | `false` | If `true`, your HTML comments will be preserved during server-side rendering. By default, they are stripped out.
 | `preserveWhitespace` | `false` | If `true`, whitespace inside and between elements is kept as you typed it, rather than removed or collapsed to a single space where possible.
 | `sourcemap` | `object | string` | An initial sourcemap that will be merged into the final output sourcemap. This is usually the preprocessor sourcemap.
-| `enableSourcemap` | `boolean | 'js' | 'css'` | If `true`, Svelte generate sourcemaps for components. Use `js` or `css` for more granular control of sourcemap generation. By default, this is `true`.
+| `enableSourcemap` | `boolean | { js: boolean; css: boolean; }` | If `true`, Svelte generate sourcemaps for components. Use an object with `js` or `css` for more granular control of sourcemap generation. By default, this is `true`.
 | `outputFilename` | `null` | A `string` used for your JavaScript sourcemap.
 | `cssOutputFilename` | `null` | A `string` used for your CSS sourcemap.
 | `sveltePath` | `"svelte"` | The location of the `svelte` package. Any imports from `svelte` or `svelte/[module]` will be modified accordingly.
diff --git a/src/compiler/compile/Component.ts b/src/compiler/compile/Component.ts
index 885c3391e41e..ef440d556015 100644
--- a/src/compiler/compile/Component.ts
+++ b/src/compiler/compile/Component.ts
@@ -36,6 +36,7 @@ import { clone } from '../utils/clone';
 import compiler_warnings from './compiler_warnings';
 import compiler_errors from './compiler_errors';
 import { extract_ignores_above_position, extract_svelte_ignore_from_comments } from '../utils/extract_svelte_ignore';
+import check_enable_sourcemap from './utils/check_enable_sourcemap';
 
 interface ComponentOptions {
 	namespace?: string;
@@ -343,7 +344,7 @@ export default class Component {
 				? { code: null, map: null }
 				: result.css;
 				
-			const jsSourcemapEnabled = compile_options.enableSourcemap === true || compile_options.enableSourcemap === 'js';
+			const jsSourcemapEnabled = check_enable_sourcemap(compile_options.enableSourcemap, 'js');
 
 			if (!jsSourcemapEnabled) {
 				js = print(program);
diff --git a/src/compiler/compile/render_dom/index.ts b/src/compiler/compile/render_dom/index.ts
index 26f9ad9de3c1..01110b95a55e 100644
--- a/src/compiler/compile/render_dom/index.ts
+++ b/src/compiler/compile/render_dom/index.ts
@@ -10,6 +10,7 @@ import { ImportDeclaration, ClassDeclaration, FunctionExpression, Node, Statemen
 import { apply_preprocessor_sourcemap } from '../../utils/mapped_code';
 import { RawSourceMap, DecodedSourceMap } from '@ampproject/remapping/dist/types/types';
 import { flatten } from '../../utils/flatten';
+import check_enable_sourcemap from '../utils/check_enable_sourcemap';
 
 export default function dom(
 	component: Component,
@@ -34,7 +35,7 @@ export default function dom(
 
 	const css = component.stylesheet.render(options.filename, !options.customElement);
 	
-	const cssSourcemapEnabled = options.enableSourcemap === true || options.enableSourcemap === 'css';
+	const cssSourcemapEnabled = check_enable_sourcemap(options.enableSourcemap, 'css');
 
 	if (cssSourcemapEnabled) {
 		css.map = apply_preprocessor_sourcemap(options.filename, css.map, options.sourcemap as string | RawSourceMap | DecodedSourceMap);
diff --git a/src/compiler/compile/render_ssr/index.ts b/src/compiler/compile/render_ssr/index.ts
index e7ee9dfe5e8e..696444e68c67 100644
--- a/src/compiler/compile/render_ssr/index.ts
+++ b/src/compiler/compile/render_ssr/index.ts
@@ -10,6 +10,7 @@ import { extract_names } from 'periscopic';
 import { walk } from 'estree-walker';
 
 import { invalidate } from '../render_dom/invalidate';
+import check_enable_sourcemap from '../utils/check_enable_sourcemap';
 
 export default function ssr(
 	component: Component,
@@ -200,7 +201,7 @@ export default function ssr(
 		main
 	].filter(Boolean);
 
-	const cssSourcemapEnabled = options.enableSourcemap === true || options.enableSourcemap === 'css';
+	const cssSourcemapEnabled = check_enable_sourcemap(options.enableSourcemap, 'css');
 	
 	const js = b`
 		${css.code ? b`
diff --git a/src/compiler/compile/utils/check_enable_sourcemap.ts b/src/compiler/compile/utils/check_enable_sourcemap.ts
new file mode 100644
index 000000000000..51f07c353ac1
--- /dev/null
+++ b/src/compiler/compile/utils/check_enable_sourcemap.ts
@@ -0,0 +1,10 @@
+import { EnableSourcemap } from '../../interfaces';
+
+export default function check_enable_sourcemap(
+  enable_sourcemap: EnableSourcemap,
+  namespace: keyof Extract<EnableSourcemap, object>
+) {
+  return typeof enable_sourcemap === 'boolean'
+    ? enable_sourcemap
+    : enable_sourcemap[namespace];
+}
diff --git a/src/compiler/interfaces.ts b/src/compiler/interfaces.ts
index 3b2f93278e76..b999fbd803dd 100644
--- a/src/compiler/interfaces.ts
+++ b/src/compiler/interfaces.ts
@@ -131,6 +131,8 @@ export interface Warning {
 
 export type ModuleFormat = 'esm' | 'cjs';
 
+export type EnableSourcemap = boolean | { js: boolean; css: boolean };
+
 export type CssHashGetter = (args: {
 	name: string;
 	filename: string | undefined;
@@ -147,7 +149,7 @@ export interface CompileOptions {
 	varsReport?: 'full' | 'strict' | false;
 
 	sourcemap?: object | string;
-	enableSourcemap?: boolean | 'js' | 'css';
+	enableSourcemap?: EnableSourcemap;
 	outputFilename?: string;
 	cssOutputFilename?: string;
 	sveltePath?: string;
diff --git a/test/sourcemaps/samples/only-css-sourcemap/_config.js b/test/sourcemaps/samples/only-css-sourcemap/_config.js
index 011ea33f9193..767e10a4b9af 100644
--- a/test/sourcemaps/samples/only-css-sourcemap/_config.js
+++ b/test/sourcemaps/samples/only-css-sourcemap/_config.js
@@ -1,5 +1,5 @@
 export default {
   compile_options: {
-    enableSourcemap: 'css'
+    enableSourcemap: { css: true }
   }
 };
diff --git a/test/sourcemaps/samples/only-js-sourcemap/_config.js b/test/sourcemaps/samples/only-js-sourcemap/_config.js
index 9a5bd733a1b5..0b3b7987f174 100644
--- a/test/sourcemaps/samples/only-js-sourcemap/_config.js
+++ b/test/sourcemaps/samples/only-js-sourcemap/_config.js
@@ -1,5 +1,5 @@
 export default {
   compile_options: {
-    enableSourcemap: 'js'
+    enableSourcemap: { js: true }
   }
 };

From 5544b15c33ead16581d0d65440ecccb53e9955c2 Mon Sep 17 00:00:00 2001
From: Conduitry <git@chor.date>
Date: Sun, 17 Oct 2021 12:55:22 -0400
Subject: [PATCH 8/8] snake_case

---
 src/compiler/compile/Component.ts        |  6 +++---
 src/compiler/compile/render_dom/index.ts | 10 +++++-----
 src/compiler/compile/render_ssr/index.ts |  6 +++---
 3 files changed, 11 insertions(+), 11 deletions(-)

diff --git a/src/compiler/compile/Component.ts b/src/compiler/compile/Component.ts
index ef440d556015..4d4cf909fda6 100644
--- a/src/compiler/compile/Component.ts
+++ b/src/compiler/compile/Component.ts
@@ -343,10 +343,10 @@ export default class Component {
 			css = compile_options.customElement
 				? { code: null, map: null }
 				: result.css;
-				
-			const jsSourcemapEnabled = check_enable_sourcemap(compile_options.enableSourcemap, 'js');
 
-			if (!jsSourcemapEnabled) {
+			const js_sourcemap_enabled = check_enable_sourcemap(compile_options.enableSourcemap, 'js');
+
+			if (!js_sourcemap_enabled) {
 				js = print(program);
 				js.map = null;
 			} else {
diff --git a/src/compiler/compile/render_dom/index.ts b/src/compiler/compile/render_dom/index.ts
index 01110b95a55e..89af0c297c51 100644
--- a/src/compiler/compile/render_dom/index.ts
+++ b/src/compiler/compile/render_dom/index.ts
@@ -34,16 +34,16 @@ export default function dom(
 	}
 
 	const css = component.stylesheet.render(options.filename, !options.customElement);
-	
-	const cssSourcemapEnabled = check_enable_sourcemap(options.enableSourcemap, 'css');
 
-	if (cssSourcemapEnabled) {
+	const css_sourcemap_enabled = check_enable_sourcemap(options.enableSourcemap, 'css');
+
+	if (css_sourcemap_enabled) {
 		css.map = apply_preprocessor_sourcemap(options.filename, css.map, options.sourcemap as string | RawSourceMap | DecodedSourceMap);
 	} else {
 		css.map = null;
 	}
 
-	const styles = cssSourcemapEnabled && component.stylesheet.has_styles && options.dev
+	const styles = css_sourcemap_enabled && component.stylesheet.has_styles && options.dev
 		? `${css.code}\n/*# sourceMappingURL=${css.map.toUrl()} */`
 		: css.code;
 
@@ -528,7 +528,7 @@ export default function dom(
 				constructor(options) {
 					super();
 
-					${css.code && b`this.shadowRoot.innerHTML = \`<style>${css.code.replace(/\\/g, '\\\\')}${cssSourcemapEnabled && options.dev ? `\n/*# sourceMappingURL=${css.map.toUrl()} */` : ''}</style>\`;`}
+					${css.code && b`this.shadowRoot.innerHTML = \`<style>${css.code.replace(/\\/g, '\\\\')}${css_sourcemap_enabled && options.dev ? `\n/*# sourceMappingURL=${css.map.toUrl()} */` : ''}</style>\`;`}
 
 					@init(this, { target: this.shadowRoot, props: ${init_props}, customElement: true }, ${definition}, ${has_create_fragment ? 'create_fragment' : 'null'}, ${not_equal}, ${prop_indexes}, null, ${dirty});
 
diff --git a/src/compiler/compile/render_ssr/index.ts b/src/compiler/compile/render_ssr/index.ts
index 696444e68c67..9d2c1cc60b68 100644
--- a/src/compiler/compile/render_ssr/index.ts
+++ b/src/compiler/compile/render_ssr/index.ts
@@ -201,13 +201,13 @@ export default function ssr(
 		main
 	].filter(Boolean);
 
-	const cssSourcemapEnabled = check_enable_sourcemap(options.enableSourcemap, 'css');
-	
+	const css_sourcemap_enabled = check_enable_sourcemap(options.enableSourcemap, 'css');
+
 	const js = b`
 		${css.code ? b`
 		const #css = {
 			code: "${css.code}",
-			map: ${cssSourcemapEnabled && css.map ? string_literal(css.map.toString()) : 'null'}
+			map: ${css_sourcemap_enabled && css.map ? string_literal(css.map.toString()) : 'null'}
 		};` : null}
 
 		${component.extract_javascript(component.ast.module)}