Require Node.js 8, use undefined instead of null, add TypeScript …

…definition (#25)

.gitattributes

@@ -1,2 +1 @@
-* text=auto
-*.js text eol=lf
+* text=auto eol=lf

.travis.yml

@@ -1,5 +1,4 @@
 language: node_js
 node_js:
+  - '10'
   - '8'
-  - '6'
-  - '4'

index.d.ts

@@ -0,0 +1,50 @@
+declare namespace detectIndent {
+	interface Indent {
+		/**
+		Type of indentation. Is `undefined` if no indentation is detected.
+		*/
+		type: 'tab' | 'space' | undefined;
+
+		/**
+		Amount of indentation, for example `2`.
+		*/
+		amount: number;
+
+		/**
+		Actual indentation.
+		*/
+		indent: string;
+	}
+}
+
+/**
+Detect the indentation of code.
+
+@param string - A string of any kind of text.
+
+@example
+```
+import * as fs from 'fs';
+import detectIndent = require('detect-indent');
+
+// {
+//     "ilove": "pizza"
+// }
+const file = fs.readFileSync('foo.json', 'utf8');
+
+// Tries to detect the indentation and falls back to a default if it can't
+const indent = detectIndent(file).indent || '    ';
+
+const json = JSON.parse(file);
+
+json.ilove = 'unicorns';
+
+fs.writeFileSync('foo.json', JSON.stringify(json, null, indent));
+// {
+//     "ilove": "unicorns"
+// }
+```
+*/
+declare function detectIndent(string: string): detectIndent.Indent;
+
+export = detectIndent;

index.js

@@ -1,39 +1,32 @@
 'use strict';
 
 // Detect either spaces or tabs but not both to properly handle tabs for indentation and spaces for alignment
-const INDENT_RE = /^(?:( )+|\t+)/;
+const INDENT_REGEX = /^(?:( )+|\t+)/;
 
 function getMostUsed(indents) {
 	let result = 0;
 	let maxUsed = 0;
 	let maxWeight = 0;
 
-	for (const entry of indents) {
-		// TODO: use destructuring when targeting Node.js 6
-		const key = entry[0];
-		const val = entry[1];
-
-		const u = val[0];
-		const w = val[1];
-
-		if (u > maxUsed || (u === maxUsed && w > maxWeight)) {
-			maxUsed = u;
-			maxWeight = w;
+	for (const [key, [usedCount, weight]] of indents) {
+		if (usedCount > maxUsed || (usedCount === maxUsed && weight > maxWeight)) {
+			maxUsed = usedCount;
+			maxWeight = weight;
 			result = key;
 		}
 	}
 
 	return result;
 }
 
-module.exports = str => {
-	if (typeof str !== 'string') {
+module.exports = string => {
+	if (typeof string !== 'string') {
 		throw new TypeError('Expected a string');
 	}
 
 	// Remember the size of previous line's indentation
-	let prev = 0;
-	let indentTypePrev;
+	let previousSize = 0;
+	let previousIndentType;
 	// Indents key (ident type + size of the indents/unindents)
 	let key;
 
@@ -48,7 +41,7 @@ module.exports = str => {
 	// }
 	const indents = new Map();
 
-	for (const line of str.split(/\n/g)) {
+	for (const line of string.split(/\n/g)) {
 		if (!line) {
 			// Ignore empty lines
 			continue;
@@ -58,11 +51,11 @@ module.exports = str => {
 		let indentType;
 		let weight;
 		let entry;
-		const matches = line.match(INDENT_RE);
+		const matches = line.match(INDENT_REGEX);
 
-		if (!matches) {
-			prev = 0;
-			indentTypePrev = '';
+		if (matches === null) {
+			previousSize = 0;
+			previousIndentType = '';
 		} else {
 			indent = matches[0].length;
 
@@ -72,22 +65,23 @@ module.exports = str => {
 				indentType = 't';
 			}
 
-			if (indentType !== indentTypePrev) {
-				prev = 0;
+			if (indentType !== previousIndentType) {
+				previousSize = 0;
 			}
-			indentTypePrev = indentType;
+
+			previousIndentType = indentType;
 
 			weight = 0;
 
-			const diff = indent - prev;
-			prev = indent;
+			const indentDifference = indent - previousSize;
+			previousSize = indent;
 
 			// Previous line have same indent?
-			if (diff === 0) {				
+			if (indentDifference === 0) {
 				weight++;
 				// We use the key from previous loop
 			} else {
-				key = indentType + String(diff > 0 ? diff : -diff);
+				key = indentType + String(indentDifference > 0 ? indentDifference : -indentDifference);
 			}
 
 			// Update the stats
@@ -98,29 +92,27 @@ module.exports = str => {
 			} else {
 				entry = [++entry[0], entry[1] + weight];
 			}
+
 			indents.set(key, entry);
-		} 
+		}
 	}
 
 	const result = getMostUsed(indents);
 
-	let amount;
+	let amount = 0;
 	let type;
-	let indent;
-	if (!result) {
-		amount = 0;
-		type = null;
-		indent = '';
-	} else {
-		amount = Number(result.substring(1));
+	let indent = '';
+
+	if (result !== 0) {
+		amount = Number(result.slice(1));
 
 		if (result[0] === 's') {
 			type = 'space';
 			indent = ' '.repeat(amount);
 		} else {
 			type = 'tab';
 			indent = '\t'.repeat(amount);
-		}		
+		}
 	}
 
 	return {

index.test-d.ts

@@ -0,0 +1,8 @@
+import {expectType} from 'tsd';
+import detectIndent = require('.');
+
+const indent = detectIndent('');
+expectType<detectIndent.Indent>(indent);
+expectType<number>(indent.amount);
+expectType<string>(indent.indent);
+expectType<'space' | 'tab' | undefined>(indent.type);

package.json

@@ -10,13 +10,14 @@
 		"url": "sindresorhus.com"
 	},
 	"engines": {
-		"node": ">=4"
+		"node": ">=8"
 	},
 	"scripts": {
-		"test": "xo && ava"
+		"test": "xo && ava && tsd"
 	},
 	"files": [
-		"index.js"
+		"index.js",
+		"index.d.ts"
 	],
 	"keywords": [
 		"indent",
@@ -32,7 +33,13 @@
 		"tab"
 	],
 	"devDependencies": {
-		"ava": "*",
-		"xo": "*"
+		"ava": "^1.4.1",
+		"tsd": "^0.7.2",
+		"xo": "^0.24.0"
+	},
+	"xo": {
+		"ignores": [
+			"fixture"
+		]
 	}
 }

readme.md

@@ -34,7 +34,7 @@ const detectIndent = require('detect-indent');
 */
 const file = fs.readFileSync('foo.json', 'utf8');
 
-// tries to detect the indentation and falls back to a default if it can't
+// Tries to detect the indentation and falls back to a default if it can't
 const indent = detectIndent(file).indent || '    ';
 
 const json = JSON.parse(file);
@@ -55,7 +55,7 @@ fs.writeFileSync('foo.json', JSON.stringify(json, null, indent));
 Accepts a string and returns an object with stats about the indentation:
 
 * `amount` {number} - Amount of indentation, for example `2`
-* `type` {string|null} - Type of indentation. Possible values are `tab`, `space` or `null` if no indentation is detected
+* `type` {'tab' | 'space' | undefined} - Type of indentation. Possible values are `'tab'`, `'space'` or `undefined` if no indentation is detected
 * `indent` {string} - Actual indentation
 
 

test.js

@@ -1,16 +1,16 @@
 import fs from 'fs';
 import path from 'path';
 import test from 'ava';
-import m from '.';
+import detectIndent from '.';
 
 const getFile = file => fs.readFileSync(path.join(__dirname, file), 'utf8');
 
 test('detect the indent of a file with space indent', t => {
-	t.is(m(getFile('fixture/space.js')).indent, '    ');
+	t.is(detectIndent(getFile('fixture/space.js')).indent, '    ');
 });
 
 test('return indentation stats for spaces', t => {
-	const stats = m(getFile('fixture/space.js'));
+	const stats = detectIndent(getFile('fixture/space.js'));
 	t.deepEqual(stats, {
 		amount: 4,
 		indent: '    ',
@@ -19,7 +19,7 @@ test('return indentation stats for spaces', t => {
 });
 
 test('return indentation stats for multiple tabs', t => {
-	const stats = m(getFile('fixture/tab-four.js'));
+	const stats = detectIndent(getFile('fixture/tab-four.js'));
 	t.deepEqual(stats, {
 		amount: 4,
 		indent: '\t\t\t\t',
@@ -28,11 +28,11 @@ test('return indentation stats for multiple tabs', t => {
 });
 
 test('detect the indent of a file with tab indent', t => {
-	t.is(m(getFile('fixture/tab.js')).indent, '\t');
+	t.is(detectIndent(getFile('fixture/tab.js')).indent, '\t');
 });
 
 test('return indentation stats for tabs', t => {
-	const stats = m(getFile('fixture/tab.js'));
+	const stats = detectIndent(getFile('fixture/tab.js'));
 	t.deepEqual(stats, {
 		amount: 1,
 		indent: '\t',
@@ -41,11 +41,11 @@ test('return indentation stats for tabs', t => {
 });
 
 test('detect the indent of a file with equal tabs and spaces', t => {
-	t.is(m(getFile('fixture/mixed-tab.js')).indent, '\t');
+	t.is(detectIndent(getFile('fixture/mixed-tab.js')).indent, '\t');
 });
 
 test('return indentation stats for equal tabs and spaces', t => {
-	const indent = m(getFile('fixture/mixed-tab.js'));
+	const indent = detectIndent(getFile('fixture/mixed-tab.js'));
 	t.deepEqual(indent, {
 		amount: 1,
 		indent: '\t',
@@ -54,12 +54,12 @@ test('return indentation stats for equal tabs and spaces', t => {
 });
 
 test('detect the indent of a file with mostly spaces', t => {
-	const stats = m(getFile('fixture/mixed-space.js'));
+	const stats = detectIndent(getFile('fixture/mixed-space.js'));
 	t.is(stats.indent, '    ');
 });
 
 test('return indentation stats for mostly spaces', t => {
-	const stats = m(getFile('fixture/mixed-space.js'));
+	const stats = detectIndent(getFile('fixture/mixed-space.js'));
 	t.deepEqual(stats, {
 		amount: 4,
 		indent: '    ',
@@ -68,12 +68,12 @@ test('return indentation stats for mostly spaces', t => {
 });
 
 test('detect the indent of a weirdly indented vendor prefixed CSS', t => {
-	const stats = m(getFile('fixture/vendor-prefixed-css.css'));
+	const stats = detectIndent(getFile('fixture/vendor-prefixed-css.css'));
 	t.is(stats.indent, '    ');
 });
 
 test('return indentation stats for various spaces', t => {
-	const stats = m(getFile('fixture/vendor-prefixed-css.css'));
+	const stats = detectIndent(getFile('fixture/vendor-prefixed-css.css'));
 	t.deepEqual(stats, {
 		amount: 4,
 		indent: '    ',
@@ -82,20 +82,20 @@ test('return indentation stats for various spaces', t => {
 });
 
 test('return `0` when there is no indentation', t => {
-	t.is(m('<ul></ul>').amount, 0);
+	t.is(detectIndent('<ul></ul>').amount, 0);
 });
 
 test('return indentation stats for no indentation', t => {
-	const stats = m('<ul></ul>');
+	const stats = detectIndent('<ul></ul>');
 	t.deepEqual(stats, {
 		amount: 0,
 		indent: '',
-		type: null
+		type: undefined
 	});
 });
 
 test('return indentation stats for fifty-fifty indented files with spaces first', t => {
-	const stats = m(getFile('fixture/fifty-fifty-space-first.js'));
+	const stats = detectIndent(getFile('fixture/fifty-fifty-space-first.js'));
 	t.deepEqual(stats, {
 		amount: 4,
 		indent: '    ',
@@ -104,7 +104,7 @@ test('return indentation stats for fifty-fifty indented files with spaces first'
 });
 
 test('return indentation stats for fifty-fifty indented files with tabs first', t => {
-	const stats = m(getFile('fixture/fifty-fifty-tab-first.js'));
+	const stats = detectIndent(getFile('fixture/fifty-fifty-tab-first.js'));
 	t.deepEqual(stats, {
 		amount: 1,
 		indent: '	',
@@ -113,7 +113,7 @@ test('return indentation stats for fifty-fifty indented files with tabs first',
 });
 
 test('return indentation stats for indented files with spaces and tabs last', t => {
-	const stats = m(getFile('fixture/space-tab-last.js'));
+	const stats = detectIndent(getFile('fixture/space-tab-last.js'));
 	t.deepEqual(stats, {
 		amount: 1,
 		indent: '	',