Fixes #3787 -- ESLint updates and linting cleanup (#3790)

* ESLint updates and linting cleanup

* Exclude test files from some linting rules for now

* Fix some TypeScript and build issues

Author: matthew-dean

packages/less/.eslintrc.js

@@ -0,0 +1,63 @@
+module.exports = {
+    'parser': '@typescript-eslint/parser',
+    'extends': 'eslint:recommended',
+    'parserOptions': {
+        'ecmaVersion': 2018,
+        'sourceType': 'module'
+    },
+    'plugins': ['@typescript-eslint'],
+    'env': {
+        'browser': true,
+        'node': true,
+        'mocha': true
+    },
+    'globals': {},
+    'rules': {
+        indent: ['error', 4, {
+            SwitchCase: 1
+        }],
+        'no-empty': ['error', { 'allowEmptyCatch': true }],
+        quotes: ['error', 'single', {
+            avoidEscape: true
+        }],
+        /**
+         * The codebase uses some while(true) statements.
+         * Refactor to remove this rule.
+         */
+        'no-constant-condition': 0,
+        /**
+         * Less combines assignments with conditionals sometimes
+         */
+        'no-cond-assign': 0,
+        /**
+         * @todo - remove when some kind of code style (XO?) is added
+         */
+        'no-multiple-empty-lines': 'error'
+    },
+    'overrides': [
+        {
+            files: ['*.ts'],
+            extends: ['plugin:@typescript-eslint/recommended'],
+            rules: {
+                /**
+                 * Suppress until Less has better-defined types
+                 * @see https://github.com/less/less.js/discussions/3786
+                 */
+                '@typescript-eslint/no-explicit-any': 0
+            }
+        },
+        {
+            files: ['test/**/*.{js,ts}', 'benchmark/index.js'],
+            /**
+             * @todo - fix later
+             */
+            rules: {
+                'no-undef': 0,
+                'no-useless-escape': 0,
+                'no-unused-vars': 0,
+                'no-redeclare': 0,
+                '@typescript-eslint/no-unused-vars': 0
+            }
+        },
+    ]
+}

packages/less/.eslintrc.json

@@ -283,7 +283,7 @@ module.exports = function(grunt) {
                 "!test/less/errors/plugin/plugin-error.js"
             ],
             options: {
-                configFile: ".eslintrc.json",
+                configFile: ".eslintrc.js",
                 fix: true
             }
         },

packages/less/Gruntfile.js

@@ -1,6 +1,6 @@
 var path = require('path'),
     fs = require('fs'),
-    now = require("performance-now");
+    now = require('performance-now');
 
 var less = require('../.');
 var file = path.join(__dirname, 'benchmark.less');
@@ -10,12 +10,12 @@ if (process.argv[2]) { file = path.join(process.cwd(), process.argv[2]) }
 fs.readFile(file, 'utf8', function (e, data) {
     var start, total;
 
-    console.log("Benchmarking...\n", path.basename(file) + " (" +
-             parseInt(data.length / 1024) + " KB)", "");
+    console.log('Benchmarking...\n', path.basename(file) + ' (' +
+             parseInt(data.length / 1024) + ' KB)', '');
 
     var renderBenchmark = []
-      , parserBenchmark = []
-      , evalBenchmark = [];
+        , parserBenchmark = []
+        , evalBenchmark = [];
 
     var totalruns = 30;
     var ignoreruns = 5;
@@ -74,13 +74,13 @@ fs.readFile(file, 'utf8', function (e, data) {
             var variation = maxtime - mintime;
             var variationperc = (variation / avgtime) * 100;
 
-            console.log("Min. Time: " + Math.round(mintime) + " ms");
-            console.log("Max. Time: " + Math.round(maxtime) + " ms");
-            console.log("Total Average Time: " + Math.round(avgtime) + " ms (" +
+            console.log('Min. Time: ' + Math.round(mintime) + ' ms');
+            console.log('Max. Time: ' + Math.round(maxtime) + ' ms');
+            console.log('Total Average Time: ' + Math.round(avgtime) + ' ms (' +
                 parseInt(1000 / avgtime *
-                data.length / 1024) + " KB\/s)");
-            console.log("+/- " + Math.round(variationperc) + "%");
-            console.log("");
+                data.length / 1024) + ' KB\/s)');
+            console.log('+/- ' + Math.round(variationperc) + '%');
+            console.log('');
         }
 
         analyze('Parsing', parserBenchmark);

packages/less/benchmark/index.js

@@ -47,7 +47,7 @@ async function buildBrowser() {
                 include: [/^.+\.min\.js$/],
                 output: {
                     comments: function(node, comment) {
-                        if (comment.type == "comment2") {
+                        if (comment.type == 'comment2') {
                             // preserve banner
                             return /@license/i.test(comment.value);
                         }

packages/less/build/rollup.js

@@ -37,11 +37,13 @@
 	"scripts": {
 		"test": "grunt test",
 		"grunt": "grunt",
+		"lint": "eslint '**/*.{ts,js}'",
+		"lint:fix": "eslint '**/*.{ts,js}' --fix",
 		"build": "npm-run-all clean compile",
 		"clean": "shx rm -rf ./lib tsconfig.tsbuildinfo",
-		"compile": "tsc -p tsconfig.json",
+		"compile": "tsc -p tsconfig.build.json",
 		"copy:root": "shx cp -rf ./dist ../../",
-		"dev": "tsc -p tsconfig.json -w",
+		"dev": "tsc -p tsconfig.build.json -w",
 		"prepublishOnly": "grunt dist"
 	},
 	"optionalDependencies": {

packages/less/package.json

@@ -3,8 +3,6 @@
  * used in the browser distributed version of less
  * to kick-start less using the browser api
  */
-/* global window, document */
-
 import defaultOptions from '../less/default-options';
 import addDefaultOptions from './add-default-options';
 import root from './index';
@@ -13,7 +11,7 @@ const options = defaultOptions();
 
 if (window.less) {
     for (const key in window.less) {
-        if (window.less.hasOwnProperty(key)) {
+        if (Object.prototype.hasOwnProperty.call(window.less, key)) {
             options[key] = window.less[key];
         }
     }

packages/less/src/less-browser/bootstrap.js

@@ -29,7 +29,7 @@ export default (window, options, logger) => {
             let vars      = cache && cache.getItem(`${path}:vars`);
 
             modifyVars = modifyVars || {};
-            vars = vars || "{}"; // if not set, treat as the JSON representation of an empty object
+            vars = vars || '{}'; // if not set, treat as the JSON representation of an empty object
 
             if (timestamp && webInfo.lastModified &&
                 (new Date(webInfo.lastModified).valueOf() ===

packages/less/src/less-browser/cache.js

@@ -11,7 +11,7 @@ export default (window, less, options) => {
         let content;
         const errors = [];
         const filename = e.filename || rootHref;
-        const filenameNoPath = filename.match(/([^\/]+(\?.*)?)$/)[1];
+        const filenameNoPath = filename.match(/([^/]+(\?.*)?)$/)[1];
 
         elem.id        = id;
         elem.className = 'less-error-message';
@@ -113,7 +113,7 @@ export default (window, less, options) => {
         }
     }
 
-    function removeErrorConsole(path) {
+    function removeErrorConsole() {
         // no action
     }
 

packages/less/src/less-browser/error-reporting.js

@@ -1,5 +1,3 @@
-/* global window, XMLHttpRequest */
-
 import AbstractFileManager from '../less/environment/abstract-file-manager.js';
 
 let options;
@@ -66,7 +64,7 @@ FileManager.prototype = Object.assign(new AbstractFileManager(), {
         fileCache = {};
     },
 
-    loadFile(filename, currentDirectory, options, environment) {
+    loadFile(filename, currentDirectory, options) {
         // TODO: Add prefix support like less-node?
         // What about multiple paths?