typescript-eslint · JoshuaKGoldberg · Sep 3, 2025 · Aug 16, 2025 · Aug 16, 2025 · Aug 16, 2025
diff --git a/packages/eslint-plugin/src/rules/no-non-null-assertion.ts b/packages/eslint-plugin/src/rules/no-non-null-assertion.ts
@@ -4,6 +4,7 @@ import { AST_NODE_TYPES } from '@typescript-eslint/utils';
 
 import {
   createRule,
+  isAssignee,
   isNonNullAssertionPunctuator,
   nullThrows,
   NullThrowsReasons,
@@ -53,7 +54,8 @@ export default createRule<[], MessageIds>({
 
         if (
           node.parent.type === AST_NODE_TYPES.MemberExpression &&
-          node.parent.object === node
+          node.parent.object === node &&
+          !isAssignee(node.parent)
         ) {
           if (!node.parent.optional) {
             if (node.parent.computed) {

diff --git a/packages/eslint-plugin/tests/rules/no-non-null-assertion.test.ts b/packages/eslint-plugin/tests/rules/no-non-null-assertion.test.ts
@@ -387,5 +387,39 @@ x?.
         },
       ],
     },
+    {
+      code: `
+document.querySelector('input')!.files = new FileList();
+      `,
+      errors: [
+        {
+          column: 1,
+          endColumn: 33,
+          line: 2,
+          messageId: 'noNonNull',
+        },
+      ],
+    },
+    {
+      code: `
+hoge.files = document.querySelector('input')!.files;
+      `,
+      errors: [
+        {
+          column: 14,
+          endColumn: 46,
+          line: 2,
+          messageId: 'noNonNull',
+          suggestions: [
+            {
+              messageId: 'suggestOptionalChain',
+              output: `
+hoge.files = document.querySelector('input')?.files;
+      `,
+            },
+          ],
+        },
+      ],
+    },
   ],
 });