Add --fix support to the rule

Running the --fix option will replace the invalid `const` declarations by `let ` declarations

Author: Joao

lib/rules/no-const-outside-module-scope.js

@@ -22,7 +22,18 @@ module.exports = {
 
         context.report({
           node: node,
-          message: '`const` should only be used in module scope (not inside functions/blocks).'
+          message: '`const` should only be used in module scope (not inside functions/blocks).',
+          fix(fixer) {
+            // Get node's text content
+            let nodeSourceCode = context.getSourceCode();
+            let nodeText = nodeSourceCode.getText(node);
+
+            // Transform the `const` to a `let` declaration
+            let fixed = nodeText.replace('const', 'let')
+
+            // // Apply and return the fix
+            return fixer.replaceText(node, fixed);
+          }
         });
       }
     };