var => const, let

.eslintrc.yml

@@ -21,6 +21,9 @@ ignorePatterns:
   - benchmark/extra/
 
 rules:
+  no-var: 2
+  prefer-const: 2
+  no-const-assign: 2
   accessor-pairs:         2
   array-bracket-spacing:  [ 2, "always", { "singleValue": true, "objectsInArrays": true, "arraysInArrays": true } ]
   block-scoped-var:       2

benchmark/benchmark.mjs

@@ -4,13 +4,13 @@
 import { createRequire } from 'node:module';
 const require = createRequire(import.meta.url);
 
-var fs        = require('fs');
-var util      = require('util');
-var Benchmark = require('benchmark');
-var ansi      = require('ansi');
-var cursor    = ansi(process.stdout);
+const fs        = require('fs');
+const util      = require('util');
+const Benchmark = require('benchmark');
+const ansi      = require('ansi');
+const cursor    = ansi(process.stdout);
 
-var IMPLS = [];
+const IMPLS = [];
 
 for (const name of fs.readdirSync(new URL('./implementations', import.meta.url)).sort()) {
   const filepath = new URL(`./implementations/${name}/index.mjs`, import.meta.url);
@@ -31,11 +31,11 @@ fs.readdirSync(new URL('./samples', import.meta.url)).sort().forEach(sample => {
 
   content.string = fs.readFileSync(filepath, 'utf8');
 
-  var title = `(${content.string.length} bytes)`;
+  const title = `(${content.string.length} bytes)`;
 
   function onComplete() { cursor.write('\n'); }
 
-  var suite = new Benchmark.Suite(
+  const suite = new Benchmark.Suite(
     title,
     {
       onStart: () => { console.log('\nSample: %s %s', sample, title); },
@@ -68,7 +68,7 @@ fs.readdirSync(new URL('./samples', import.meta.url)).sort().forEach(sample => {
 
 
 function select(patterns) {
-  var result = [];
+  const result = [];
 
   if (!(patterns instanceof Array)) {
     patterns = [ patterns ];
@@ -91,7 +91,7 @@ function select(patterns) {
 
 
 function run(files) {
-  var selected = select(files);
+  const selected = select(files);
 
   if (selected.length > 0) {
     console.log('Selected samples: (%d of %d)', selected.length, SAMPLES.length);

benchmark/implementations/commonmark-reference/index.mjs

@@ -3,8 +3,8 @@ const require = createRequire(import.meta.url);
 
 const commonmark = require('../../extra/lib/node_modules/commonmark');
 
-var parser = new commonmark.Parser();
-var renderer = new commonmark.HtmlRenderer();
+const parser = new commonmark.Parser();
+const renderer = new commonmark.HtmlRenderer();
 
 export function run(data) {
   return renderer.render(parser.parse(data));

benchmark/implementations/current-commonmark/index.mjs

@@ -1,10 +1,10 @@
 import markdownit from '../../../index.mjs';
 
-var md = markdownit('commonmark');
+const md = markdownit('commonmark');
 
 // Replace normalizers to more primitive, for more "honest" compare.
 // Default ones can cause 1.5x slowdown.
-var encode = md.utils.lib.mdurl.encode;
+const encode = md.utils.lib.mdurl.encode;
 
 md.normalizeLink     = function (url) { return encode(url); };
 md.normalizeLinkText = function (str) { return str; };

benchmark/implementations/current/index.mjs

@@ -1,6 +1,6 @@
 import markdownit from '../../../index.mjs';
 
-var md = markdownit({
+const md = markdownit({
   html: true,
   linkify: true,
   typographer: true

benchmark/implementations/markdown-it-2.2.1-commonmark/index.mjs

@@ -3,7 +3,7 @@ const require = createRequire(import.meta.url);
 
 const markdownit = require('../../extra/lib/node_modules/markdown-it');
 
-var md = markdownit('commonmark');
+const md = markdownit('commonmark');
 
 export function run(data) {
   return md.render(data);

benchmark/profile.mjs

@@ -4,14 +4,14 @@
 import { readFileSync } from 'fs';
 import markdownit from '../index.mjs';
 
-var md = markdownit({
+const md = markdownit({
   html: true,
   linkify: false,
   typographer: false
 });
 
-var data = readFileSync(new URL('../test/fixtures/commonmark/spec.txt', import.meta.url), 'utf8');
+const data = readFileSync(new URL('../test/fixtures/commonmark/spec.txt', import.meta.url), 'utf8');
 
-for (var i = 0; i < 20; i++) {
+for (let i = 0; i < 20; i++) {
   md.render(data);
 }

bin/markdown-it.mjs

@@ -7,7 +7,7 @@ import markdownit from '../index.mjs';
 
 ////////////////////////////////////////////////////////////////////////////////
 
-var cli = new argparse.ArgumentParser({
+const cli = new argparse.ArgumentParser({
   prog: 'markdown-it',
   add_help: true
 });
@@ -48,13 +48,13 @@ cli.add_argument('-o', '--output', {
   default: '-'
 });
 
-var options = cli.parse_args();
+const options = cli.parse_args();
 
 
 function readFile(filename, encoding, callback) {
   if (options.file === '-') {
     // read from stdin
-    var chunks = [];
+    const chunks = [];
 
     process.stdin.on('data', function (chunk) { chunks.push(chunk); });
 
@@ -70,7 +70,7 @@ function readFile(filename, encoding, callback) {
 ////////////////////////////////////////////////////////////////////////////////
 
 readFile(options.file, 'utf8', function (err, input) {
-  var output, md;
+  let output;
 
   if (err) {
     if (err.code === 'ENOENT') {
@@ -86,7 +86,7 @@ readFile(options.file, 'utf8', function (err, input) {
     process.exit(1);
   }
 
-  md = markdownit({
+  const md = markdownit({
     html: !options.no_html,
     xhtmlOut: false,
     typographer: options.typographer,

lib/common/html_re.mjs

@@ -1,25 +1,25 @@
 // Regexps to match html elements
 
-var attr_name     = '[a-zA-Z_:][a-zA-Z0-9:._-]*';
+const attr_name     = '[a-zA-Z_:][a-zA-Z0-9:._-]*';
 
-var unquoted      = '[^"\'=<>`\\x00-\\x20]+';
-var single_quoted = "'[^']*'";
-var double_quoted = '"[^"]*"';
+const unquoted      = '[^"\'=<>`\\x00-\\x20]+';
+const single_quoted = "'[^']*'";
+const double_quoted = '"[^"]*"';
 
-var attr_value  = '(?:' + unquoted + '|' + single_quoted + '|' + double_quoted + ')';
+const attr_value  = '(?:' + unquoted + '|' + single_quoted + '|' + double_quoted + ')';
 
-var attribute   = '(?:\\s+' + attr_name + '(?:\\s*=\\s*' + attr_value + ')?)';
+const attribute   = '(?:\\s+' + attr_name + '(?:\\s*=\\s*' + attr_value + ')?)';
 
-var open_tag    = '<[A-Za-z][A-Za-z0-9\\-]*' + attribute + '*\\s*\\/?>';
+const open_tag    = '<[A-Za-z][A-Za-z0-9\\-]*' + attribute + '*\\s*\\/?>';
 
-var close_tag   = '<\\/[A-Za-z][A-Za-z0-9\\-]*\\s*>';
-var comment     = '<!---->|<!--(?:-?[^>-])(?:-?[^-])*-->';
-var processing  = '<[?][\\s\\S]*?[?]>';
-var declaration = '<![A-Z]+\\s+[^>]*>';
-var cdata       = '<!\\[CDATA\\[[\\s\\S]*?\\]\\]>';
+const close_tag   = '<\\/[A-Za-z][A-Za-z0-9\\-]*\\s*>';
+const comment     = '<!---->|<!--(?:-?[^>-])(?:-?[^-])*-->';
+const processing  = '<[?][\\s\\S]*?[?]>';
+const declaration = '<![A-Z]+\\s+[^>]*>';
+const cdata       = '<!\\[CDATA\\[[\\s\\S]*?\\]\\]>';
 
-var HTML_TAG_RE = new RegExp('^(?:' + open_tag + '|' + close_tag + '|' + comment +
+const HTML_TAG_RE = new RegExp('^(?:' + open_tag + '|' + close_tag + '|' + comment +
                         '|' + processing + '|' + declaration + '|' + cdata + ')');
-var HTML_OPEN_CLOSE_TAG_RE = new RegExp('^(?:' + open_tag + '|' + close_tag + ')');
+const HTML_OPEN_CLOSE_TAG_RE = new RegExp('^(?:' + open_tag + '|' + close_tag + ')');
 
 export { HTML_TAG_RE, HTML_OPEN_CLOSE_TAG_RE };

lib/common/utils.mjs

@@ -10,7 +10,7 @@ function _class(obj) { return Object.prototype.toString.call(obj); }
 
 function isString(obj) { return _class(obj) === '[object String]'; }
 
-var _hasOwnProperty = Object.prototype.hasOwnProperty;
+const _hasOwnProperty = Object.prototype.hasOwnProperty;
 
 function has(object, key) {
   return _hasOwnProperty.call(object, key);
@@ -19,7 +19,7 @@ function has(object, key) {
 // Merge objects
 //
 function assign(obj /*from1, from2, from3, ...*/) {
-  var sources = Array.prototype.slice.call(arguments, 1);
+  const sources = Array.prototype.slice.call(arguments, 1);
 
   sources.forEach(function (source) {
     if (!source) { return; }
@@ -65,27 +65,25 @@ function fromCodePoint(c) {
   /*eslint no-bitwise:0*/
   if (c > 0xffff) {
     c -= 0x10000;
-    var surrogate1 = 0xd800 + (c >> 10),
-        surrogate2 = 0xdc00 + (c & 0x3ff);
+    const surrogate1 = 0xd800 + (c >> 10),
+          surrogate2 = 0xdc00 + (c & 0x3ff);
 
     return String.fromCharCode(surrogate1, surrogate2);
   }
   return String.fromCharCode(c);
 }
 
 
-var UNESCAPE_MD_RE  = /\\([!"#$%&'()*+,\-.\/:;<=>?@[\\\]^_`{|}~])/g;
-var ENTITY_RE       = /&([a-z#][a-z0-9]{1,31});/gi;
-var UNESCAPE_ALL_RE = new RegExp(UNESCAPE_MD_RE.source + '|' + ENTITY_RE.source, 'gi');
+const UNESCAPE_MD_RE  = /\\([!"#$%&'()*+,\-.\/:;<=>?@[\\\]^_`{|}~])/g;
+const ENTITY_RE       = /&([a-z#][a-z0-9]{1,31});/gi;
+const UNESCAPE_ALL_RE = new RegExp(UNESCAPE_MD_RE.source + '|' + ENTITY_RE.source, 'gi');
 
-var DIGITAL_ENTITY_TEST_RE = /^#((?:x[a-f0-9]{1,8}|[0-9]{1,8}))$/i;
+const DIGITAL_ENTITY_TEST_RE = /^#((?:x[a-f0-9]{1,8}|[0-9]{1,8}))$/i;
 
 
 function replaceEntityPattern(match, name) {
-  var decoded, code;
-
   if (name.charCodeAt(0) === 0x23/* # */ && DIGITAL_ENTITY_TEST_RE.test(name)) {
-    code = name[1].toLowerCase() === 'x' ?
+    const code = name[1].toLowerCase() === 'x' ?
       parseInt(name.slice(2), 16) : parseInt(name.slice(1), 10);
 
     if (isValidEntityCode(code)) {
@@ -95,7 +93,7 @@ function replaceEntityPattern(match, name) {
     return match;
   }
 
-  decoded = decodeHTML(match);
+  const decoded = decodeHTML(match);
   if (decoded !== match) {
     return decoded;
   }
@@ -125,9 +123,9 @@ function unescapeAll(str) {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-var HTML_ESCAPE_TEST_RE = /[&<>"]/;
-var HTML_ESCAPE_REPLACE_RE = /[&<>"]/g;
-var HTML_REPLACEMENTS = {
+const HTML_ESCAPE_TEST_RE = /[&<>"]/;
+const HTML_ESCAPE_REPLACE_RE = /[&<>"]/g;
+const HTML_REPLACEMENTS = {
   '&': '&amp;',
   '<': '&lt;',
   '>': '&gt;',
@@ -147,7 +145,7 @@ function escapeHtml(str) {
 
 ////////////////////////////////////////////////////////////////////////////////
 
-var REGEXP_ESCAPE_RE = /[.?*+^$[\]\\(){}|-]/g;
+const REGEXP_ESCAPE_RE = /[.?*+^$[\]\\(){}|-]/g;
 
 function escapeRE(str) {
   return str.replace(REGEXP_ESCAPE_RE, '\\$&');

lib/helpers/parse_link_destination.mjs

@@ -4,14 +4,15 @@
 import { unescapeAll } from '../common/utils.mjs';
 
 export default function parseLinkDestination(str, start, max) {
-  var code, level,
-      pos = start,
-      result = {
-        ok: false,
-        pos: 0,
-        lines: 0,
-        str: ''
-      };
+  let code;
+  let pos = start;
+
+  const result = {
+    ok: false,
+    pos: 0,
+    lines: 0,
+    str: ''
+  };
 
   if (str.charCodeAt(pos) === 0x3C /* < */) {
     pos++;
@@ -39,7 +40,7 @@ export default function parseLinkDestination(str, start, max) {
 
   // this should be ... } else { ... branch
 
-  level = 0;
+  let level = 0;
   while (pos < max) {
     code = str.charCodeAt(pos);
 

lib/helpers/parse_link_label.mjs

@@ -5,10 +5,10 @@
 //
 
 export default function parseLinkLabel(state, start, disableNested) {
-  var level, found, marker, prevPos,
-      labelEnd = -1,
-      max = state.posMax,
-      oldPos = state.pos;
+  let level, found, marker, prevPos;
+
+  const max = state.posMax;
+  const oldPos = state.pos;
 
   state.pos = start + 1;
   level = 1;
@@ -36,6 +36,8 @@ export default function parseLinkLabel(state, start, disableNested) {
     }
   }
 
+  let labelEnd = -1;
+
   if (found) {
     labelEnd = state.pos;
   }

lib/helpers/parse_link_title.mjs

@@ -5,16 +5,16 @@ import { unescapeAll } from '../common/utils.mjs';
 
 
 export default function parseLinkTitle(str, start, max) {
-  var code,
-      marker,
-      lines = 0,
-      pos = start,
-      result = {
-        ok: false,
-        pos: 0,
-        lines: 0,
-        str: ''
-      };
+  let code, marker;
+  let lines = 0;
+  let pos = start;
+
+  const result = {
+    ok: false,
+    pos: 0,
+    lines: 0,
+    str: ''
+  };
 
   if (pos >= max) { return result; }