Enforce const (and let) via eslint

.eslintrc.json

@@ -1,12 +1,15 @@
 {
+    "root": true,
     "rules": {
         "indent": [ 2, "tab", { "SwitchCase": 1 } ],
         "linebreak-style": [ 2, "unix" ],
         "semi": [ 2, "always" ],
         "keyword-spacing": [ 2, { "before": true, "after": true } ],
         "space-before-blocks": [ 2, "always" ],
         "no-mixed-spaces-and-tabs": [ 2, "smart-tabs" ],
-        "no-cond-assign": [ 0 ]
+        "no-cond-assign": [ 0 ],
+        "prefer-const": 2,
+        "no-var": 2
     },
     "env": {
         "es6": true,
@@ -21,7 +24,8 @@
       {
         "files": ["register.js"],
         "rules": {
-          "no-console": [ 0 ]
+          "no-console": [ 0 ],
+          "no-var": [ 0 ]
         }
       }
     ]

bin/.eslintrc.yaml

@@ -0,0 +1,3 @@
+rules:
+  no-console: "off"
+  no-var: "off"

bin/buble

@@ -18,7 +18,7 @@ var command = minimist(process.argv.slice(2), {
 if (command.help || (process.argv.length <= 2 && process.stdin.isTTY)) {
 	require('./showHelp')();
 } else if (command.version) {
-	console.log('Bublé version ' + require('../package.json').version); // eslint-disable-line no-console
+	console.log('Bublé version ' + require('../package.json').version);
 } else {
 	require('./runBuble')(command);
 }

bin/handleError.js

@@ -1,7 +1,7 @@
 var chalk = require('chalk');
 
 function print(msg) {
-	console.error(chalk.red(msg)); // eslint-disable-line no-console
+	console.error(chalk.red(msg));
 }
 
 var handlers = {
@@ -44,11 +44,11 @@ module.exports = function handleError(err) {
 		print(err.message || err);
 
 		if (err.stack) {
-			console.error(chalk.grey(err.stack)); // eslint-disable-line no-console
+			console.error(chalk.grey(err.stack));
 		}
 	}
 
-	console.error( // eslint-disable-line no-console
+	console.error(
 		'Type ' +
 			chalk.cyan('buble --help') +
 			' for help, or visit https://buble.surge.sh/guide/'

bin/runBuble.js

@@ -71,7 +71,7 @@ function write(result, to, command) {
 	if (to) {
 		fs.writeFileSync(to, result.code);
 	} else {
-		console.log(result.code); // eslint-disable-line no-console
+		console.log(result.code);
 	}
 }
 

bin/showHelp.js

@@ -11,6 +11,6 @@ module.exports = function() {
 			.toString()
 			.replace('<%= version %>', require('../package.json').version);
 
-		console.log('\n' + help + '\n'); // eslint-disable-line no-console
+		console.log('\n' + help + '\n');
 	});
 };

src/index.js

@@ -36,7 +36,7 @@ export function target(target) {
 		bitmask &= support;
 	});
 
-	let transforms = Object.create(null);
+	const transforms = Object.create(null);
 	features.forEach((name, i) => {
 		transforms[name] = !(bitmask & (1 << i));
 	});
@@ -60,7 +60,7 @@ export function transform(source, options = {}) {
 			allowReturnOutsideFunction: true,
 			onComment: (block, text) => {
 				if (!jsx) {
-					let match = /@jsx\s+([^\s]+)/.exec(text);
+					const match = /@jsx\s+([^\s]+)/.exec(text);
 					if (match) jsx = match[1];
 				}
 			}
@@ -72,7 +72,7 @@ export function transform(source, options = {}) {
 		throw err;
 	}
 
-	let transforms = target(options.target || {});
+	const transforms = target(options.target || {});
 	Object.keys(options.transforms || {}).forEach(name => {
 		if (name === 'modules') {
 			if (!('moduleImport' in options.transforms))

src/program/BlockStatement.js

@@ -122,7 +122,7 @@ export default class BlockStatement extends Node {
 	transpile(code, transforms) {
 		const indentation = this.getIndentation();
 
-		let introStatementGenerators = [];
+		const introStatementGenerators = [];
 
 		if (this.argumentsAlias) {
 			introStatementGenerators.push((start, prefix, suffix) => {
@@ -212,7 +212,7 @@ export default class BlockStatement extends Node {
 			start = this.start + 1;
 		}
 
-		let prefix = `\n${indentation}`;
+		const prefix = `\n${indentation}`;
 		let suffix = ';';
 		introStatementGenerators.forEach((fn, i) => {
 			if (i === introStatementGenerators.length - 1) suffix = `;\n`;
@@ -305,7 +305,7 @@ export default class BlockStatement extends Node {
 		Object.keys(this.scope.blockScopedDeclarations).forEach(name => {
 			const declarations = this.scope.blockScopedDeclarations[name];
 
-			for (let declaration of declarations) {
+			for (const declaration of declarations) {
 				let cont = false; // TODO implement proper continue...
 
 				if (declaration.kind === 'for.let') {

src/program/Node.js

@@ -1,7 +1,7 @@
 // used for debugging, without the noise created by
 // circular references
 function toJSON(node) {
-	var obj = {};
+	const obj = {};
 
 	Object.keys(node).forEach(key => {
 		if (
@@ -79,7 +79,7 @@ export default class Node {
 	}
 
 	initialise(transforms) {
-		for (var key of this.keys) {
+		for (const key of this.keys) {
 			const value = this[key];
 
 			if (Array.isArray(value)) {

src/program/types/ArrayExpression.js

@@ -28,7 +28,7 @@ export default class ArrayExpression extends Node {
 		if (transforms.spreadRest) {
 			// erase trailing comma after last array element if not an array hole
 			if (this.elements.length) {
-				let lastElement = this.elements[this.elements.length - 1];
+				const lastElement = this.elements[this.elements.length - 1];
 				if (
 					lastElement &&
 					/\s*,/.test(code.original.slice(lastElement.end, this.end))

src/program/types/ClassBody.js

@@ -49,9 +49,9 @@ export default class ClassBody extends Node {
 				if (!inFunctionExpression) code.appendLeft(constructor.end, ';');
 			}
 
-			let namedFunctions =
+			const namedFunctions =
 				this.program.options.namedFunctionExpressions !== false;
-			let namedConstructor =
+			const namedConstructor =
 				namedFunctions ||
 				this.parent.superClass ||
 				this.parent.type !== 'ClassDeclaration';
@@ -86,8 +86,8 @@ export default class ClassBody extends Node {
 
 			const scope = this.findScope(false);
 
-			let prototypeGettersAndSetters = [];
-			let staticGettersAndSetters = [];
+			const prototypeGettersAndSetters = [];
+			const staticGettersAndSetters = [];
 			let prototypeAccessors;
 			let staticAccessors;
 
@@ -99,7 +99,7 @@ export default class ClassBody extends Node {
 				}
 
 				if (method.kind === 'constructor') {
-					let constructorName = namedConstructor ? ' ' + name : '';
+					const constructorName = namedConstructor ? ' ' + name : '';
 					code.overwrite(
 						method.key.start,
 						method.key.end,
@@ -198,8 +198,8 @@ export default class ClassBody extends Node {
 			});
 
 			if (prototypeGettersAndSetters.length || staticGettersAndSetters.length) {
-				let intro = [];
-				let outro = [];
+				const intro = [];
+				const outro = [];
 
 				if (prototypeGettersAndSetters.length) {
 					intro.push(

src/program/types/ForInStatement.js

@@ -47,7 +47,7 @@ export default class ForInStatement extends LoopStatement {
 
 		code.prependRight(pattern.end, isDeclaration ? ref : `var ${ref}`);
 
-		let statementGenerators = [];
+		const statementGenerators = [];
 		destructure(
 			code,
 			id => scope.createIdentifier(id),

src/program/types/ForOfStatement.js

@@ -55,7 +55,7 @@ export default class ForOfStatement extends LoopStatement {
 		const isDeclaration = this.left.type === 'VariableDeclaration';
 		const maybeDestructuring = isDeclaration ? this.left.declarations[0].id : this.left;
 		if (maybeDestructuring.type !== 'Identifier') {
-			let statementGenerators = [];
+			const statementGenerators = [];
 			const ref = scope.createIdentifier('ref');
 			destructure(
 				code,

src/program/types/NewExpression.js

@@ -26,7 +26,7 @@ export default class NewExpression extends Node {
 		if (transforms.spreadRest && this.arguments.length) {
 			const firstArgument = this.arguments[0];
 			const isNew = true;
-			let hasSpreadElements = spread(
+			const hasSpreadElements = spread(
 				code,
 				this.arguments,
 				firstArgument.start,

src/program/types/TemplateLiteral.js

@@ -8,7 +8,7 @@ export default class TemplateLiteral extends Node {
 			transforms.templateString &&
 			this.parent.type !== 'TaggedTemplateExpression'
 		) {
-			let ordered = this.expressions
+			const ordered = this.expressions
 				.concat(this.quasis)
 				.sort((a, b) => a.start - b.start || a.end - b.end)
 				.filter((node, i) => {

src/program/types/VariableDeclaration.js

@@ -49,7 +49,7 @@ export default class VariableDeclaration extends Node {
 
 					c = declarator.start;
 
-					let statementGenerators = [];
+					const statementGenerators = [];
 
 					if (simple) {
 						code.remove(declarator.id.end, declarator.end);
@@ -72,7 +72,7 @@ export default class VariableDeclaration extends Node {
 						statementGenerators
 					);
 
-					let prefix = inline ? 'var ' : '';
+					const prefix = inline ? 'var ' : '';
 					let suffix = inline ? `, ` : `;\n${i0}`;
 					statementGenerators.forEach((fn, j) => {
 						if (

src/program/types/VariableDeclarator.js

@@ -13,7 +13,7 @@ export default class VariableDeclarator extends Node {
 
 	transpile(code, transforms) {
 		if (!this.init && transforms.letConst && this.parent.kind !== 'var') {
-			let inLoop = this.findNearest(
+			const inLoop = this.findNearest(
 				/Function|^For(In|Of)?Statement|^(?:Do)?WhileStatement/
 			);
 			if (

src/utils/getSnippet.js

@@ -1,5 +1,5 @@
 function pad(num, len) {
-	let result = String(num);
+	const result = String(num);
 	return result + repeat(' ', len - result.length);
 }
 

src/utils/locate.js

@@ -1,13 +1,13 @@
 export default function locate(source, index) {
-	var lines = source.split('\n');
-	var len = lines.length;
+	const lines = source.split('\n');
+	const len = lines.length;
 
-	var lineStart = 0;
-	var i;
+	let lineStart = 0;
+	let i;
 
 	for (i = 0; i < len; i += 1) {
-		var line = lines[i];
-		var lineEnd = lineStart + line.length + 1; // +1 for newline
+		const line = lines[i];
+		const lineEnd = lineStart + line.length + 1; // +1 for newline
 
 		if (lineEnd > index) {
 			return { line: i + 1, column: index - lineStart, char: i };

src/utils/reserved.js

@@ -1,4 +1,4 @@
-let reserved = Object.create(null);
+const reserved = Object.create(null);
 'do if in for let new try var case else enum eval null this true void with await break catch class const false super throw while yield delete export import public return static switch typeof default extends finally package private continue debugger function arguments interface protected implements instanceof'
 	.split(' ')
 	.forEach(word => (reserved[word] = true));

src/utils/spread.js

@@ -31,7 +31,7 @@ export default function spread(
 
 	if (isNew) {
 		for (i = 0; i < elements.length; i += 1) {
-			let element = elements[i];
+			const element = elements[i];
 			if (element.type === 'SpreadElement') {
 				code.remove(element.start, element.argument.start);
 			} else {

test/.eslintrc.json

@@ -2,5 +2,8 @@
   "env": {
       "mocha": true
   },
-  "rules": { "no-console": "off" }
+  "rules": {
+    "no-console": "off",
+    "no-var": "off"
+  }
 }