Add "// @ts-check" for better VS Code experience, address corresponding issues.

lib/markdownlint.js

@@ -1,3 +1,5 @@
+// @ts-check
+
 "use strict";
 
 var fs = require("fs");
@@ -228,13 +230,14 @@ function lintContent(
         "range": range || null
       });
     }
-    errors.add = function add(lineNumber) {
+    var errorHelpers = {
+      "add": function add(lineNumber) {
         addError(lineNumber);
-    };
-    errors.addDetail = function addDetail(lineNumber, detail) {
+      },
+      "addDetail": function addDetail(lineNumber, detail) {
         addError(lineNumber, detail);
-    };
-    errors.addDetailIf =
+      },
+      "addDetailIf":
         function addDetailIf(lineNumber, expected, actual, detail, range) {
           if (expected !== actual) {
             addError(
@@ -244,8 +247,8 @@ function lintContent(
               null,
               range);
           }
-      };
-    errors.addContext =
+        },
+      "addContext":
         function addContext(lineNumber, context, left, right, range) {
           if (context.length <= 30) {
             // Nothing to do
@@ -257,8 +260,12 @@ function lintContent(
             context = context.substr(0, 30) + "...";
           }
           addError(lineNumber, null, context, range);
+        },
+      "count": function count() {
+        return errors.length;
+      }
     };
-    rule.func(params, errors);
+    rule.func(params, errorHelpers);
     // Record any errors (significant performance benefit from length check)
     if (errors.length) {
       errors.sort(lineNumberComparison);
@@ -336,22 +343,7 @@ function lintFile(
   }
 }
 
-// Callback used as a sentinel by markdownlintSync
-function markdownlintSynchronousCallback() {
-  // Unreachable; no code path in the synchronous case passes err
-  // if (err) {
-  //   throw err; // Synchronous APIs throw
-  // }
-}
-
-/**
- * Lint specified Markdown files.
- *
- * @param {Object} options Configuration options.
- * @param {Function} callback Callback (err, result) function.
- * @returns {void}
- */
-function markdownlint(options, callback) {
+function lintInput(options, synchronous, callback) {
   // Normalize inputs
   options = options || {};
   callback = callback || function noop() {};
@@ -368,7 +360,6 @@ function markdownlint(options, callback) {
   var noInlineConfig = !!options.noInlineConfig;
   var resultVersion = (options.resultVersion === undefined) ?
     1 : options.resultVersion;
-  var synchronous = (callback === markdownlintSynchronousCallback);
   var results = new Results();
   // Helper to lint the next file in the array
   function lintFilesArray() {
@@ -405,10 +396,17 @@ function markdownlint(options, callback) {
   });
   // Lint files
   lintFilesArray();
-  // Return results
-  if (synchronous) {
-    return results;
 }
+
+/**
+ * Lint specified Markdown files.
+ *
+ * @param {Object} options Configuration options.
+ * @param {Function} callback Callback (err, result) function.
+ * @returns {void}
+ */
+function markdownlint(options, callback) {
+  return lintInput(options, false, callback);
 }
 
 /**
@@ -418,7 +416,15 @@ function markdownlint(options, callback) {
  * @returns {Object} Result object.
  */
 function markdownlintSync(options) {
-  return markdownlint(options, markdownlintSynchronousCallback);
+  var results = null;
+  lintInput(options, true, function callback(error, res) {
+    // Unreachable; no code path in the synchronous case passes error
+    // if (error) {
+    //   throw error;
+    // }
+    results = res;
+  });
+  return results;
 }
 
 /**
@@ -477,7 +483,7 @@ function readConfigSync(file) {
 }
 
 // Export a/synchronous APIs
+markdownlint.sync = markdownlintSync;
+markdownlint.readConfig = readConfig;
+markdownlint.readConfigSync = readConfigSync;
 module.exports = markdownlint;
-module.exports.sync = markdownlintSync;
-module.exports.readConfig = readConfig;
-module.exports.readConfigSync = readConfigSync;

lib/rules.js

@@ -1,3 +1,5 @@
+// @ts-check
+
 "use strict";
 
 var shared = require("./shared");
@@ -942,24 +944,28 @@ module.exports = [
                 !re.test(t.children[1].content)) {
               errors.addContext(t.lineNumber, t.children[1].content);
             }
+            return base;
           };
         } else if (token.type === "blockquote_open") {
           return function inBlockquote(t) {
             if (t.type !== "blockquote_close") {
               return inBlockquote;
             }
+            return base;
           };
         } else if (token.type === "list_item_open") {
           return function inListItem(t) {
             if (t.type !== "list_item_close") {
               return inListItem;
             }
+            return base;
           };
         }
+        return base;
       }
       var state = base;
       params.tokens.forEach(function forToken(token) {
-        state = state(token) || base;
+        state = state(token);
       });
     }
   },
@@ -1147,7 +1153,7 @@ module.exports = [
         var i = 0;
         var optional = false;
         forEachHeading(params, function forHeading(heading, content) {
-          if (!errors.length) {
+          if (!errors.count()) {
             var actual = levels[heading.tag] + " " + content;
             var expected = requiredHeaders[i++] || "[None]";
             if (expected === "*") {
@@ -1161,7 +1167,7 @@ module.exports = [
             }
           }
         });
-        if ((i < requiredHeaders.length) && !errors.length) {
+        if ((i < requiredHeaders.length) && !errors.count()) {
           errors.addContext(params.lines.length, requiredHeaders[i]);
         }
       }

lib/shared.js

@@ -1,3 +1,5 @@
+// @ts-check
+
 "use strict";
 
 // Regular expression for matching common newline characters