Replace assign/clone helpers with object spread syntax.

.eslintrc.json

@@ -1,7 +1,7 @@
 {
   "parser": "espree",
   "parserOptions": {
-    "ecmaVersion": 6
+    "ecmaVersion": 2018
   },
   "env": {
     "node": true,

.gitignore

@@ -5,4 +5,5 @@ demo/markdownlint-browser.min.js
 lib-es3
 node_modules
 npm-debug.log
+.nyc_output
 .vscode

helpers/helpers.js

@@ -24,20 +24,6 @@ module.exports.orderedListItemMarkerRe = /^[\s>]*0*(\d+)[.)]/;
 // readFile options for reading with the UTF-8 encoding
 module.exports.utf8Encoding = { "encoding": "utf8" };
 
-// Applies key/value pairs from src to dst, returning dst
-function assign(dst, src) {
-  Object.keys(src).forEach(function forKey(key) {
-    dst[key] = src[key];
-  });
-  return dst;
-}
-module.exports.assign = assign;
-
-// Clones the key/value pairs of obj, returning the clone
-module.exports.clone = function clone(obj) {
-  return assign({}, obj);
-};
-
 // Returns true iff the input is a number
 module.exports.isNumber = function isNumber(obj) {
   return typeof obj === "number";

lib/markdownlint.js

@@ -271,7 +271,7 @@ function getEnabledRulesPerLineNumber(
     if (!noInlineConfig) {
       let match = helpers.inlineCommentRe.exec(line);
       if (match) {
-        enabledRules = helpers.clone(enabledRules);
+        enabledRules = { ...enabledRules };
         while (match) {
           forMatch(match);
           match = helpers.inlineCommentRe.exec(line);
@@ -613,7 +613,10 @@ function readConfig(file, parsers, callback) {
         if (errr) {
           return callback(errr);
         }
-        return callback(null, helpers.assign(extendsConfig, config));
+        return callback(null, {
+          ...extendsConfig,
+          ...config
+        });
       });
     }
     return callback(null, config);
@@ -639,9 +642,13 @@ function readConfigSync(file, parsers) {
   const configExtends = config.extends;
   if (configExtends) {
     delete config.extends;
-    return helpers.assign(
+    return {
-      readConfigSync(path.resolve(path.dirname(file), configExtends), parsers),
+      ...readConfigSync(
-      config);
+        path.resolve(path.dirname(file), configExtends),
+        parsers
+      ),
+      ...config
+    };
   }
   return config;
 }

package.json

@@ -13,7 +13,7 @@
   "bugs": "https://github.com/DavidAnson/markdownlint/issues",
   "scripts": {
     "test": "nodeunit test/markdownlint-test.js",
-    "test-cover": "istanbul cover node_modules/nodeunit/bin/nodeunit test/markdownlint-test.js",
+    "test-cover": "nyc node_modules/nodeunit/bin/nodeunit test/markdownlint-test.js",
     "test-extra": "nodeunit test/markdownlint-test-extra.js",
     "debug": "node debug node_modules/nodeunit/bin/nodeunit",
     "lint": "eslint 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\" example",
@@ -34,7 +34,6 @@
     "cpy-cli": "~2.0.0",
     "eslint": "~5.15.3",
     "glob": "~7.1.3",
-    "istanbul": "~0.4.5",
     "js-yaml": "~3.13.0",
     "markdown-it-for-inline": "~0.1.1",
     "markdown-it-katex": "~2.0.3",
@@ -42,6 +41,7 @@
     "markdown-it-sup": "~1.0.0",
     "markdownlint-rule-helpers": "~0.1.0",
     "nodeunit": "~0.11.3",
+    "nyc": "~14.1.0",
     "rimraf": "~2.6.3",
     "toml": "~3.0.0",
     "tv4": "~1.3.0",

test/markdownlint-test.js

@@ -47,8 +47,10 @@ function createTestForFile(file) {
         })
       .then(
         function lintWithConfig(config) {
-          const mergedConfig =
+          const mergedConfig = {
-            helpers.assign(helpers.clone(defaultConfig), config);
+            ...defaultConfig,
+            ...config
+          };
           return promisify(markdownlint, {
             "files": [ file ],
             "config": mergedConfig,
@@ -1651,11 +1653,11 @@ module.exports.configMultiple = function configMultiple(test) {
   markdownlint.readConfig("./test/config/config-grandparent.json",
     function callback(err, actual) {
       test.ifError(err);
-      const expected = helpers.assign(
+      const expected = {
-        helpers.assign(
+        ...require("./config/config-child.json"),
-          helpers.assign({}, require("./config/config-child.json")),
+        ...require("./config/config-parent.json"),
-          require("./config/config-parent.json")),
+        ...require("./config/config-grandparent.json")
-        require("./config/config-grandparent.json"));
+      };
       delete expected.extends;
       test.deepEqual(actual, expected, "Config object not correct.");
       test.done();
@@ -1729,11 +1731,11 @@ module.exports.configMultipleYaml = function configMultipleYaml(test) {
     [ require("js-yaml").safeLoad ],
     function callback(err, actual) {
       test.ifError(err);
-      const expected = helpers.assign(
+      const expected = {
-        helpers.assign(
+        ...require("./config/config-child.json"),
-          helpers.assign({}, require("./config/config-child.json")),
+        ...require("./config/config-parent.json"),
-          require("./config/config-parent.json")),
+        ...require("./config/config-grandparent.json")
-        require("./config/config-grandparent.json"));
+      };
       delete expected.extends;
       test.deepEqual(actual, expected, "Config object not correct.");
       test.done();
@@ -1747,11 +1749,11 @@ module.exports.configMultipleHybrid = function configMultipleHybrid(test) {
     [ JSON.parse, require("toml").parse, require("js-yaml").safeLoad ],
     function callback(err, actual) {
       test.ifError(err);
-      const expected = helpers.assign(
+      const expected = {
-        helpers.assign(
+        ...require("./config/config-child.json"),
-          helpers.assign({}, require("./config/config-child.json")),
+        ...require("./config/config-parent.json"),
-          require("./config/config-parent.json")),
+        ...require("./config/config-grandparent.json")
-        require("./config/config-grandparent.json"));
+      };
       delete expected.extends;
       test.deepEqual(actual, expected, "Config object not correct.");
       test.done();
@@ -1796,11 +1798,11 @@ module.exports.configMultipleSync = function configMultipleSync(test) {
   test.expect(1);
   const actual =
     markdownlint.readConfigSync("./test/config/config-grandparent.json");
-  const expected = helpers.assign(
+  const expected = {
-    helpers.assign(
+    ...require("./config/config-child.json"),
-      helpers.assign({}, require("./config/config-child.json")),
+    ...require("./config/config-parent.json"),
-      require("./config/config-parent.json")),
+    ...require("./config/config-grandparent.json")
-    require("./config/config-grandparent.json"));
+  };
   delete expected.extends;
   test.deepEqual(actual, expected, "Config object not correct.");
   test.done();
@@ -1877,11 +1879,11 @@ module.exports.configMultipleYamlSync = function configMultipleYamlSync(test) {
   test.expect(1);
   const actual = markdownlint.readConfigSync(
     "./test/config/config-grandparent.yaml", [ require("js-yaml").safeLoad ]);
-  const expected = helpers.assign(
+  const expected = {
-    helpers.assign(
+    ...require("./config/config-child.json"),
-      helpers.assign({}, require("./config/config-child.json")),
+    ...require("./config/config-parent.json"),
-      require("./config/config-parent.json")),
+    ...require("./config/config-grandparent.json")
-    require("./config/config-grandparent.json"));
+  };
   delete expected.extends;
   test.deepEqual(actual, expected, "Config object not correct.");
   test.done();
@@ -1893,11 +1895,11 @@ function configMultipleHybridSync(test) {
   const actual = markdownlint.readConfigSync(
     "./test/config/config-grandparent-hybrid.yaml",
     [ JSON.parse, require("toml").parse, require("js-yaml").safeLoad ]);
-  const expected = helpers.assign(
+  const expected = {
-    helpers.assign(
+    ...require("./config/config-child.json"),
-      helpers.assign({}, require("./config/config-child.json")),
+    ...require("./config/config-parent.json"),
-      require("./config/config-parent.json")),
+    ...require("./config/config-grandparent.json")
-    require("./config/config-grandparent.json"));
+  };
   delete expected.extends;
   test.deepEqual(actual, expected, "Config object not correct.");
   test.done();
@@ -2306,7 +2308,7 @@ module.exports.customRulesBadProperty = function customRulesBadProperty(test) {
   ].forEach(function forProperty(property) {
     const propertyName = property[0];
     property[1].forEach(function forPropertyValue(propertyValue) {
-      const badRule = helpers.clone(customRules.anyBlockquote);
+      const badRule = { ...customRules.anyBlockquote };
       badRule[propertyName] = propertyValue;
       const options = {
         "customRules": [ badRule ]