Add lint rules from eslint-plugin-unicorn.

.eslintrc.json

@@ -8,7 +8,8 @@
   },
   "plugins": [
     "jsdoc",
-    "node"
+    "node",
+    "unicorn"
   ],
   "extends": [
     "eslint:all",
@@ -113,6 +114,62 @@
     "node/prefer-global/url-search-params": "error",
     "node/prefer-global/url": "error",
     "node/prefer-promises/dns": "error",
-    "node/prefer-promises/fs": "off"
+    "node/prefer-promises/fs": "off",
+
+    "unicorn/better-regex": "off",
+    "unicorn/catch-error-name": "error",
+    "unicorn/consistent-function-scoping": "off",
+    "unicorn/custom-error-definition": "error",
+    "unicorn/error-message": "error",
+    "unicorn/escape-case": "error",
+    "unicorn/expiring-todo-comments": "error",
+    "unicorn/explicit-length-check": "error",
+    "unicorn/filename-case": "off",
+    "unicorn/import-index": "error",
+    "unicorn/new-for-builtins": "error",
+    "unicorn/no-abusive-eslint-disable": "error",
+    "unicorn/no-array-instanceof": "error",
+    "unicorn/no-console-spaces": "error",
+    "unicorn/no-fn-reference-in-iterator": "off",
+    "unicorn/no-for-loop": "error",
+    "unicorn/no-hex-escape": "error",
+    "unicorn/no-keyword-prefix": "off",
+    "unicorn/no-nested-ternary": "error",
+    "unicorn/no-new-buffer": "error",
+    "unicorn/no-null": "off",
+    "unicorn/no-object-as-default-parameter": "error",
+    "unicorn/no-process-exit": "error",
+    "unicorn/no-reduce": "error",
+    "unicorn/no-unreadable-array-destructuring": "error",
+    "unicorn/no-unsafe-regex": "off",
+    "unicorn/no-unused-properties": "error",
+    "unicorn/no-useless-undefined": "error",
+    "unicorn/no-zero-fractions": "error",
+    "unicorn/number-literal-case": "error",
+    "unicorn/prefer-add-event-listener": "error",
+    "unicorn/prefer-array-find": "error",
+    "unicorn/prefer-dataset": "error",
+    "unicorn/prefer-event-key": "error",
+    "unicorn/prefer-flat-map": "error",
+    "unicorn/prefer-includes": "error",
+    "unicorn/prefer-modern-dom-apis": "error",
+    "unicorn/prefer-negative-index": "error",
+    "unicorn/prefer-node-append": "error",
+    "unicorn/prefer-node-remove": "error",
+    "unicorn/prefer-number-properties": "error",
+    "unicorn/prefer-optional-catch-binding": "error",
+    "unicorn/prefer-query-selector": "error",
+    "unicorn/prefer-reflect-apply": "error",
+    "unicorn/prefer-replace-all": "off",
+    "unicorn/prefer-set-has": "error",
+    "unicorn/prefer-spread": "error",
+    "unicorn/prefer-starts-ends-with": "error",
+    "unicorn/prefer-string-slice": "off",
+    "unicorn/prefer-text-content": "error",
+    "unicorn/prefer-trim-start-end": "off",
+    "unicorn/prefer-type-error": "error",
+    "unicorn/prevent-abbreviations": "off",
+    "unicorn/string-content": "error",
+    "unicorn/throw-new-error": "error"
   }
 }

demo/default.js

@@ -196,7 +196,8 @@
       if (hashPrefix === decodedHash.substring(0, hashPrefix.length)) {
         markdown.value = decodedHash.substring(hashPrefix.length);
       }
-    } catch (ex) {
+      /* eslint-disable-next-line unicorn/prefer-optional-catch-binding */
+    } catch (error) {
       // Invalid
     }
   }
@@ -205,7 +206,8 @@
   try {
     /* eslint-disable-next-line no-new */
     new URL(rulesMd);
-  } catch (ex) {
+    /* eslint-disable-next-line unicorn/prefer-optional-catch-binding */
+  } catch (error) {
     markdown.value = [
       "# Sorry",
       "",

demo/markdownlint-browser.js

@@ -2782,10 +2782,10 @@ module.exports = {
             // Close current run
             var content = line.substring(emphasisIndex, matchIndex);
             if (!emphasisLength) {
-                content = content.trimStart();
+                content = content.trimLeft();
             }
             if (!match) {
-                content = content.trimEnd();
+                content = content.trimRight();
             }
             var leftSpace = leftSpaceRe.test(content);
             var rightSpace = rightSpaceRe.test(content);

lib/markdownlint.js

@@ -154,7 +154,7 @@ function removeFrontMatter(content, frontMatter) {
       const contentMatched = frontMatterMatch[0];
       content = content.slice(contentMatched.length);
       frontMatterLines = contentMatched.split(helpers.newLineRe);
-      if (frontMatterLines.length &&
+      if ((frontMatterLines.length > 0) &&
           (frontMatterLines[frontMatterLines.length - 1] === "")) {
         frontMatterLines.length--;
       }
@@ -343,7 +343,8 @@ function getEnabledRulesPerLineNumber(
           ...config,
           ...json
         };
-      } catch (ex) {
+      // eslint-disable-next-line unicorn/prefer-optional-catch-binding
+      } catch (error) {
         // Ignore parse errors for inline configuration
       }
     }
@@ -459,7 +460,7 @@ function lintContent(
   resultVersion,
   callback) {
   // Remove UTF-8 byte order marker (if present)
-  content = content.replace(/^\ufeff/, "");
+  content = content.replace(/^\uFEFF/, "");
   // Remove front matter
   const removeFrontMatterResult = removeFrontMatter(content, frontMatter);
   const frontMatterLines = removeFrontMatterResult.frontMatterLines;
@@ -582,17 +583,17 @@ function lintContent(
     if (handleRuleFailures) {
       try {
         rule.function(params, onError);
-      } catch (ex) {
+      } catch (error) {
         onError({
           "lineNumber": 1,
-          "detail": `This rule threw an exception: ${ex.message}`
+          "detail": `This rule threw an exception: ${error.message}`
         });
       }
     } else {
       rule.function(params, onError);
     }
     // Record any errors (significant performance benefit from length check)
-    if (errors.length) {
+    if (errors.length > 0) {
       errors.sort(lineNumberComparison);
       const filteredErrors = errors
         .filter((resultVersion === 3) ?
@@ -624,7 +625,7 @@ function lintContent(
           }
           return errorObject;
         });
-      if (filteredErrors.length) {
+      if (filteredErrors.length > 0) {
         if (resultVersion === 0) {
           result[ruleNameFriendly] = filteredErrors;
         } else {
@@ -636,9 +637,9 @@ function lintContent(
   // Run all rules
   try {
     ruleList.forEach(forRule);
-  } catch (ex) {
+  } catch (error) {
     cache.clear();
-    return callback(ex);
+    return callback(error);
   }
   cache.clear();
   return callback(null, result);
@@ -819,8 +820,8 @@ function parseConfiguration(name, content, parsers) {
   (parsers || [ JSON.parse ]).every((parser) => {
     try {
       config = parser(content);
-    } catch (ex) {
+    } catch (error) {
-      errors.push(ex.message);
+      errors.push(error.message);
     }
     return !config;
   });

lib/md001.js

@@ -11,7 +11,7 @@ module.exports = {
   "function": function MD001(params, onError) {
     let prevLevel = 0;
     filterTokens(params, "heading_open", function forToken(token) {
-      const level = parseInt(token.tag.slice(1), 10);
+      const level = Number.parseInt(token.tag.slice(1), 10);
       if (prevLevel && (level > prevLevel)) {
         addErrorDetailIf(onError, token.lineNumber,
           "h" + (prevLevel + 1), "h" + level);

lib/md012.js

@@ -13,7 +13,7 @@ module.exports = {
     const maximum = Number(params.config.maximum || 1);
     let count = 0;
     forEachLine(lineMetadata(), (line, lineIndex, inCode) => {
-      count = (inCode || line.trim().length) ? 0 : count + 1;
+      count = (inCode || (line.trim().length > 0)) ? 0 : count + 1;
       if (maximum < count) {
         addErrorDetailIf(
           onError,

lib/md037.js

@@ -32,10 +32,10 @@ module.exports = {
       // Close current run
       let content = line.substring(emphasisIndex, matchIndex);
       if (!emphasisLength) {
-        content = content.trimStart();
+        content = content.trimLeft();
       }
       if (!match) {
-        content = content.trimEnd();
+        content = content.trimRight();
       }
       const leftSpace = leftSpaceRe.test(content);
       const rightSpace = rightSpaceRe.test(content);

package.json

@@ -17,7 +17,7 @@
     "test-cover": "c8 --check-coverage --branches 100 --functions 100 --lines 100 --statements 100 node test/markdownlint-test.js",
     "test-declaration": "cd example/typescript && tsc && node type-check.js",
     "test-extra": "node test/markdownlint-test-extra.js",
-    "lint": "eslint --max-warnings 0 lib helpers test schema && eslint --env browser --global markdownit --global markdownlint --rule \"no-unused-vars: 0, no-extend-native: 0, max-statements: 0, no-console: 0, no-var: 0\" demo && eslint --rule \"no-console: 0, no-invalid-this: 0, no-shadow: 0, object-property-newline: 0, node/no-missing-require: 0, node/no-extraneous-require: 0\" example",
+    "lint": "eslint --max-warnings 0 lib helpers test schema && eslint --env browser --global markdownit --global markdownlint --rule \"no-unused-vars: 0, no-extend-native: 0, max-statements: 0, no-console: 0, no-var: 0, unicorn/prefer-add-event-listener: 0, unicorn/prefer-query-selector: 0, unicorn/prefer-replace-all: 0\" demo && eslint --rule \"no-console: 0, no-invalid-this: 0, no-shadow: 0, object-property-newline: 0, node/no-missing-require: 0, node/no-extraneous-require: 0\" example",
     "ci": "npm run test-cover && npm run lint && npm run test-declaration",
     "build-config-schema": "node schema/build-config-schema.js",
     "build-declaration": "tsc --allowJs --declaration --outDir declaration --resolveJsonModule lib/markdownlint.js && cpy declaration/lib/markdownlint.d.ts lib && rimraf declaration",
@@ -43,6 +43,7 @@
     "eslint": "~7.8.1",
     "eslint-plugin-jsdoc": "~30.3.1",
     "eslint-plugin-node": "~11.1.0",
+    "eslint-plugin-unicorn": "~21.0.0",
     "globby": "~11.0.1",
     "js-yaml": "~3.14.0",
     "make-dir-cli": "~2.0.0",

test/markdownlint-test-repos.js

@@ -55,7 +55,7 @@ function lintTestRepo(test, globPatterns, configPath) {
     };
     return markdownlintPromise(options).then((results) => {
       const resultsString = results.toString();
-      if (resultsString.length) {
+      if (resultsString.length > 0) {
         // eslint-disable-next-line no-console
         console.log(resultsString);
       }

test/markdownlint-test.js

@@ -24,7 +24,7 @@ const configSchema = require("../schema/markdownlint-config-schema.json");
 const homepage = packageJson.homepage;
 const version = packageJson.version;
 
-const deprecatedRuleNames = [ "MD002", "MD006" ];
+const deprecatedRuleNames = new Set([ "MD002", "MD006" ]);
 
 /**
  * Create a test function for the specified test file.
@@ -128,7 +128,11 @@ function createTestForFile(file) {
               while ((match = regex.exec(line))) {
                 const rule = match[1];
                 const errors = results[rule] || [];
-                errors.push(match[2] ? parseInt(match[2], 10) : lineNum + 1);
+                errors.push(
+                  match[2] ?
+                    Number.parseInt(match[2], 10) :
+                    lineNum + 1
+                );
                 results[rule] = errors;
               }
             });
@@ -1504,7 +1508,7 @@ tape("readme", (test) => {
               let expected = "**[" + ruleName + "](doc/Rules.md#" +
                 ruleName.toLowerCase() + ")** *" +
                 ruleAliases.join("/") + "* - " + rule.description;
-              if (deprecatedRuleNames.includes(ruleName)) {
+              if (deprecatedRuleNames.has(ruleName)) {
                 expected = "~~" + expected + "~~";
               }
               test.equal(token.content, expected, "Rule mismatch.");
@@ -1566,7 +1570,7 @@ tape("rules", (test) => {
               "Missing rule implementation for " + token.content + ".");
             const ruleName = rule.names[0];
             let headingContent = ruleName + " - " + rule.description;
-            if (deprecatedRuleNames.includes(ruleName)) {
+            if (deprecatedRuleNames.has(ruleName)) {
               headingContent = "~~" + headingContent + "~~";
             }
             test.equal(token.content,
@@ -1580,16 +1584,16 @@ tape("rules", (test) => {
               });
               ruleUsesParams.sort();
             }
-          } else if (/^Tags: /.test(token.content) && rule) {
+          } else if (token.content.startsWith("Tags: ") && rule) {
             test.deepEqual(token.content.split(tagAliasParameterRe).slice(1),
               rule.tags, "Tag mismatch for rule " + rule.names + ".");
             ruleHasTags = true;
-          } else if (/^Aliases: /.test(token.content) && rule) {
+          } else if (token.content.startsWith("Aliases: ") && rule) {
             test.deepEqual(token.content.split(tagAliasParameterRe).slice(1),
               rule.names.slice(1),
               "Alias mismatch for rule " + rule.names + ".");
             ruleHasAliases = true;
-          } else if (/^Parameters: /.test(token.content) && rule) {
+          } else if (token.content.startsWith("Parameters: ") && rule) {
             let inDetails = false;
             const parameters = token.content.split(tagAliasParameterRe)
               .slice(1)

test/rules/lint-javascript.js

@@ -17,7 +17,7 @@ const languageJavaScript = /js|javascript/i;
 function cleanJsdocRulesFromEslintConfig(config) {
   const cleanedConfig = { ...config };
   for (const rule in config.rules) {
-    if (/^(jsdoc|node)\//.test(rule)) {
+    if (/^(jsdoc|node|unicorn)\//.test(rule)) {
       delete cleanedConfig.rules[rule];
     }
   }