Fix: prevent fixing to incorrect code (fixes eslint#11069)

captain-yossarian · Nov 11, 2018 · 9a8d8d6 · 9a8d8d6
1 parent e18c827
commit 9a8d8d6
Showing 1 changed file with 25 additions and 0 deletions.
diff --git a/lib/rules/no-else-return.js b/lib/rules/no-else-return.js
@@ -12,6 +12,20 @@
 const astUtils = require("../util/ast-utils");
 const FixTracker = require("../util/fix-tracker");
 
+//------------------------------------------------------------------------------
+// Helpers
+//------------------------------------------------------------------------------
+
+/**
+ * @param {Token} token - The token to check
+ * @returns {boolean} `true` if keyword let or const exist
+ */
+function isVariableDeclaration(token) {
+    const variableDeclaration = token.value === "let" || token.value === "const";
+
+    return token.type === "Keyword" && variableDeclaration;
+}
+
 //------------------------------------------------------------------------------
 // Rule Definition
 //------------------------------------------------------------------------------
@@ -88,6 +102,17 @@ module.exports = {
                     }
 
                     const endToken = sourceCode.getLastToken(node);
+
+                    /**
+                     * If else block includes block scope local variable declaration [let or const],
+                     * then it is not safe to remove else keyword [issue 11069]
+                     */
+                    const isDeclarationInside = sourceCode.getTokensBetween(startToken, endToken).findIndex(isVariableDeclaration) > -1;
+
+                    if (isDeclarationInside) {
+                        return null;
+                    }
+
                     const lastTokenOfElseBlock = sourceCode.getTokenBefore(endToken);
 
                     if (lastTokenOfElseBlock.value !== ";") {