Start introducing new blockBindings option

src/finalisers/amd.ts

@@ -22,7 +22,6 @@ export default function amd(
 		namedExportsMode,
 		outro,
 		snippets,
-		varOrConst,
 		warn
 	}: FinaliserOptions,
 	{
@@ -64,7 +63,6 @@ export default function amd(
 	magicString.prepend(
 		`${intro}${getInteropBlock(
 			dependencies,
-			varOrConst,
 			interop,
 			externalLiveBindings,
 			freeze,

src/finalisers/cjs.ts

@@ -19,8 +19,7 @@ export default function cjs(
 		isModuleFacade,
 		namedExportsMode,
 		outro,
-		snippets,
-		varOrConst
+		snippets
 	}: FinaliserOptions,
 	{
 		compact,
@@ -45,10 +44,9 @@ export default function cjs(
 	if (namespaceMarkers) {
 		namespaceMarkers += n + n;
 	}
-	const importBlock = getImportBlock(dependencies, snippets, compact, varOrConst);
+	const importBlock = getImportBlock(dependencies, snippets, compact);
 	const interopBlock = getInteropBlock(
 		dependencies,
-		varOrConst,
 		interop,
 		externalLiveBindings,
 		freeze,
@@ -76,9 +74,8 @@ export default function cjs(
 
 function getImportBlock(
 	dependencies: ChunkDependencies,
-	{ n, _ }: GenerateCodeSnippets,
-	compact: boolean,
-	varOrConst: string
+	{ _, cnst, n }: GenerateCodeSnippets,
+	compact: boolean
 ): string {
 	let importBlock = '';
 	let definingVariable = false;
@@ -90,8 +87,7 @@ function getImportBlock(
 			definingVariable = false;
 			importBlock += `require('${id}')`;
 		} else {
-			importBlock +=
-				compact && definingVariable ? ',' : `${importBlock ? `;${n}` : ''}${varOrConst} `;
+			importBlock += compact && definingVariable ? ',' : `${importBlock ? `;${n}` : ''}${cnst} `;
 			definingVariable = true;
 			importBlock += `${name}${_}=${_}require('${id}')`;
 		}

src/finalisers/iife.ts

@@ -80,7 +80,6 @@ export default function iife(
 	const useStrict = strict ? `${t}'use strict';${n}` : '';
 	const interopBlock = getInteropBlock(
 		dependencies,
-		varOrConst,
 		interop,
 		externalLiveBindings,
 		freeze,

src/finalisers/shared/getInteropBlock.ts

@@ -10,7 +10,6 @@ import {
 
 export default function getInteropBlock(
 	dependencies: ModuleDeclarationDependency[],
-	varOrConst: string,
 	interop: GetInterop,
 	externalLiveBindings: boolean,
 	freeze: boolean,
@@ -19,7 +18,7 @@ export default function getInteropBlock(
 	indent: string,
 	snippets: GenerateCodeSnippets
 ): string {
-	const { _, n } = snippets;
+	const { _, cnst, n } = snippets;
 	const neededInteropHelpers = new Set<string>();
 	const interopStatements: string[] = [];
 	const addInteropStatement = (
@@ -29,7 +28,7 @@ export default function getInteropBlock(
 	): void => {
 		neededInteropHelpers.add(helper);
 		interopStatements.push(
-			`${varOrConst} ${helperVariableName}${_}=${_}/*#__PURE__*/${helper}(${dependencyVariableName});`
+			`${cnst} ${helperVariableName}${_}=${_}/*#__PURE__*/${helper}(${dependencyVariableName});`
 		);
 	};
 	for (const {

src/finalisers/system.ts

@@ -155,7 +155,6 @@ const getStarExcludes = ({ dependencies, exports }: ModuleDeclarations): Set<str
 	return starExcludes;
 };
 
-// TODO Lukas _starExcludes must not conflict with local variables.
 const getStarExcludesBlock = (
 	starExcludes: Set<string> | null,
 	varOrConst: string,

src/finalisers/umd.ts

@@ -42,7 +42,6 @@ export default function umd(
 		namedExportsMode,
 		outro,
 		snippets,
-		varOrConst,
 		warn
 	}: FinaliserOptions,
 	{
@@ -181,7 +180,6 @@ export default function umd(
 	magicString.prepend(
 		`${intro}${getInteropBlock(
 			dependencies,
-			varOrConst,
 			interop,
 			externalLiveBindings,
 			freeze,

src/rollup/types.d.ts

@@ -583,6 +583,7 @@ type GeneratedCodePreset = 'es5' | 'es2015';
 
 interface NormalizedGeneratedCodeOptions {
 	arrowFunctions: boolean;
+	blockBindings: boolean;
 	objectShorthand: boolean;
 	reservedNamesAsProps: boolean;
 }

src/utils/generateCodeSnippets.ts

@@ -3,6 +3,7 @@ import { RESERVED_NAMES } from './reservedNames';
 
 export interface GenerateCodeSnippets {
 	_: string;
+	cnst: string;
 	directReturnFunctionRight: string;
 	n: string;
 	namedDirectReturnFunctionRight: string;
@@ -27,18 +28,20 @@ export interface GenerateCodeSnippets {
 	getPropertyAccess(name: string): string;
 }
 
+// TODO Lukas deprecate preferConst
 export function getGenerateCodeSnippets({
 	compact,
-	generatedCode: { arrowFunctions, objectShorthand, reservedNamesAsProps }
+	generatedCode: { arrowFunctions, blockBindings, objectShorthand, reservedNamesAsProps },
+	preferConst
 }: NormalizedOutputOptions): GenerateCodeSnippets {
 	const { _, n, s } = compact ? { _: '', n: '', s: '' } : { _: ' ', n: '\n', s: ';' };
+	const cnst = blockBindings || preferConst ? 'const' : 'var';
 
-	// TODO Lukas use const
 	const getFunctionIntro: GenerateCodeSnippets['getFunctionIntro'] = arrowFunctions
 		? (params, { isAsync, name }) => {
 				const singleParam = params.length === 1;
 				const asyncString = isAsync ? `async${singleParam ? ' ' : _}` : '';
-				return `${name ? `var ${name}${_}=${_}` : ''}${asyncString}${
+				return `${name ? `${cnst} ${name}${_}=${_}` : ''}${asyncString}${
 					singleParam ? params[0] : `(${params.join(`,${_}`)})`
 				}${_}=>${_}`;
 		  }
@@ -64,6 +67,7 @@ export function getGenerateCodeSnippets({
 
 	return {
 		_,
+		cnst,
 		directReturnFunctionRight,
 		getDirectReturnFunctionLeft,
 		getDirectReturnIifeLeft: (params, returned, { needsArrowReturnParens, needsWrappedFunction }) =>

src/utils/options/normalizeOutputOptions.ts

@@ -324,6 +324,7 @@ const getGeneratedCode = (config: OutputOptions): NormalizedOutputOptions['gener
 	);
 	return {
 		arrowFunctions: configWithPreset.arrowFunctions === true,
+		blockBindings: configWithPreset.blockBindings === true,
 		objectShorthand: configWithPreset.objectShorthand === true,
 		reservedNamesAsProps: configWithPreset.reservedNamesAsProps === true
 	};

src/utils/options/options.ts

@@ -78,11 +78,13 @@ export const generatedCodePresets: {
 } = {
 	es2015: {
 		arrowFunctions: true,
+		blockBindings: true,
 		objectShorthand: true,
 		reservedNamesAsProps: true
 	},
 	es5: {
 		arrowFunctions: false,
+		blockBindings: false,
 		objectShorthand: false,
 		reservedNamesAsProps: false
 	}

test/form/samples/generated-code/block-bindings-false/_config.js

@@ -0,0 +1,10 @@
+module.exports = {
+	description: 'does not use block bindings',
+	options: {
+		external: ['external'],
+		output: {
+			generatedCode: { arrowFunctions: true, blockBindings: false },
+			name: 'bundle'
+		}
+	}
+};

test/form/samples/generated-code/block-bindings-false/_expected/amd.js

@@ -0,0 +1,9 @@
+define(['external'], (foo => { 'use strict';
+
+	var _interopDefaultLegacy = e => e && typeof e === 'object' && 'default' in e ? e : { 'default': e };
+
+	var foo__default = /*#__PURE__*/_interopDefaultLegacy(foo);
+
+	console.log(foo__default["default"]);
+
+}));

test/form/samples/generated-code/block-bindings-false/_expected/cjs.js

@@ -0,0 +1,9 @@
+'use strict';
+
+var foo = require('external');
+
+var _interopDefaultLegacy = e => e && typeof e === 'object' && 'default' in e ? e : { 'default': e };
+
+var foo__default = /*#__PURE__*/_interopDefaultLegacy(foo);
+
+console.log(foo__default["default"]);

test/form/samples/generated-code/block-bindings-false/_expected/es.js

@@ -0,0 +1,3 @@
+import foo from 'external';
+
+console.log(foo);

test/form/samples/generated-code/block-bindings-false/_expected/iife.js

@@ -0,0 +1,10 @@
+(foo => {
+	'use strict';
+
+	var _interopDefaultLegacy = e => e && typeof e === 'object' && 'default' in e ? e : { 'default': e };
+
+	var foo__default = /*#__PURE__*/_interopDefaultLegacy(foo);
+
+	console.log(foo__default["default"]);
+
+})(foo);

test/form/samples/generated-code/block-bindings-false/_expected/system.js

@@ -0,0 +1,14 @@
+System.register('bundle', ['external'], (() => {
+	'use strict';
+	var foo;
+	return {
+		setters: [(module => {
+			foo = module["default"];
+		})],
+		execute: (() => {
+
+			console.log(foo);
+
+		})
+	};
+}));

test/form/samples/generated-code/block-bindings-false/_expected/umd.js

@@ -0,0 +1,13 @@
+((global, factory) => {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory(require('external')) :
+	typeof define === 'function' && define.amd ? define(['external'], factory) :
+	(global = typeof globalThis !== 'undefined' ? globalThis : global || self, factory(global.foo));
+})(this, (foo => { 'use strict';
+
+	var _interopDefaultLegacy = e => e && typeof e === 'object' && 'default' in e ? e : { 'default': e };
+
+	var foo__default = /*#__PURE__*/_interopDefaultLegacy(foo);
+
+	console.log(foo__default["default"]);
+
+}));

test/form/samples/generated-code/block-bindings-false/main.js

@@ -0,0 +1,2 @@
+import foo from 'external';
+console.log(foo);

test/form/samples/generated-code/block-bindings-true/_config.js

@@ -0,0 +1,10 @@
+module.exports = {
+	description: 'uses block bindings',
+	options: {
+		external: ['external'],
+		output: {
+			generatedCode: { arrowFunctions: true, blockBindings: true },
+			name: 'bundle'
+		}
+	}
+};

test/form/samples/generated-code/block-bindings-true/_expected/amd.js

@@ -0,0 +1,9 @@
+define(['external'], (foo => { 'use strict';
+
+	const _interopDefaultLegacy = e => e && typeof e === 'object' && 'default' in e ? e : { 'default': e };
+
+	const foo__default = /*#__PURE__*/_interopDefaultLegacy(foo);
+
+	console.log(foo__default["default"]);
+
+}));

test/form/samples/generated-code/block-bindings-true/_expected/cjs.js

@@ -0,0 +1,9 @@
+'use strict';
+
+const foo = require('external');
+
+const _interopDefaultLegacy = e => e && typeof e === 'object' && 'default' in e ? e : { 'default': e };
+
+const foo__default = /*#__PURE__*/_interopDefaultLegacy(foo);
+
+console.log(foo__default["default"]);

test/form/samples/generated-code/block-bindings-true/_expected/es.js

@@ -0,0 +1,3 @@
+import foo from 'external';
+
+console.log(foo);

test/form/samples/generated-code/block-bindings-true/_expected/iife.js

@@ -0,0 +1,10 @@
+(foo => {
+	'use strict';
+
+	const _interopDefaultLegacy = e => e && typeof e === 'object' && 'default' in e ? e : { 'default': e };
+
+	const foo__default = /*#__PURE__*/_interopDefaultLegacy(foo);
+
+	console.log(foo__default["default"]);
+
+})(foo);

test/form/samples/generated-code/block-bindings-true/_expected/system.js

@@ -0,0 +1,14 @@
+System.register('bundle', ['external'], (() => {
+	'use strict';
+	var foo;
+	return {
+		setters: [(module => {
+			foo = module["default"];
+		})],
+		execute: (() => {
+
+			console.log(foo);
+
+		})
+	};
+}));

test/form/samples/generated-code/block-bindings-true/_expected/umd.js

@@ -0,0 +1,13 @@
+((global, factory) => {
+	typeof exports === 'object' && typeof module !== 'undefined' ? factory(require('external')) :
+	typeof define === 'function' && define.amd ? define(['external'], factory) :
+	(global = typeof globalThis !== 'undefined' ? globalThis : global || self, factory(global.foo));
+})(this, (foo => { 'use strict';
+
+	const _interopDefaultLegacy = e => e && typeof e === 'object' && 'default' in e ? e : { 'default': e };
+
+	const foo__default = /*#__PURE__*/_interopDefaultLegacy(foo);
+
+	console.log(foo__default["default"]);
+
+}));

test/form/samples/generated-code/block-bindings-true/main.js

@@ -0,0 +1 @@
+../../generated-code/block-bindings-false/main.js

test/function/samples/output-options-hook/_config.js

@@ -32,6 +32,7 @@ module.exports = {
 					freeze: true,
 					generatedCode: {
 						arrowFunctions: false,
+						blockBindings: false,
 						objectShorthand: false,
 						reservedNamesAsProps: false
 					},