typescript-eslint · dvorsky · Oct 9, 2019 · bradzacher · Oct 9, 2019 · bradzacher
diff --git a/packages/eslint-plugin/README.md b/packages/eslint-plugin/README.md
@@ -145,7 +145,7 @@ Then you should add `airbnb` (or `airbnb-base`) to your `extends` section of `.e
 | [`@typescript-eslint/await-thenable`](./docs/rules/await-thenable.md)                                     | Disallows awaiting a value that is not a Thenable                                                                                                   | :heavy_check_mark: |          | :thought_balloon: |
 | [`@typescript-eslint/ban-ts-ignore`](./docs/rules/ban-ts-ignore.md)                                       | Bans “// @ts-ignore” comments from being used                                                                                                       | :heavy_check_mark: |          |                   |
 | [`@typescript-eslint/ban-types`](./docs/rules/ban-types.md)                                               | Bans specific types from being used                                                                                                                 | :heavy_check_mark: | :wrench: |                   |
-| [`@typescript-eslint/brace-style`](./docs/rules/brace-style.md)                                               | Enforce consistent brace style for blocks                                                                                                                  |                    | :wrench: |                   |
+| [`@typescript-eslint/brace-style`](./docs/rules/brace-style.md)                                               | Enforce consistent brace style for blocks                                                                                                       |                    | :wrench: |                   |
 | [`@typescript-eslint/camelcase`](./docs/rules/camelcase.md)                                               | Enforce camelCase naming convention                                                                                                                 | :heavy_check_mark: |          |                   |
 | [`@typescript-eslint/class-name-casing`](./docs/rules/class-name-casing.md)                               | Require PascalCased class and interface names                                                                                                       | :heavy_check_mark: |          |                   |
 | [`@typescript-eslint/consistent-type-assertions`](./docs/rules/consistent-type-assertions.md)             | Enforces consistent usage of type assertions.                                                                                                       | :heavy_check_mark: |          |                   |
@@ -160,6 +160,7 @@ Then you should add `airbnb` (or `airbnb-base`) to your `extends` section of `.e
 | [`@typescript-eslint/member-naming`](./docs/rules/member-naming.md)                                       | Enforces naming conventions for class members by visibility                                                                                         |                    |          |                   |
 | [`@typescript-eslint/member-ordering`](./docs/rules/member-ordering.md)                                   | Require a consistent member declaration order                                                                                                       |                    |          |                   |
 | [`@typescript-eslint/no-array-constructor`](./docs/rules/no-array-constructor.md)                         | Disallow generic `Array` constructors                                                                                                               | :heavy_check_mark: | :wrench: |                   |
+| [`@typescript-eslint/no-dynamic-delete`](./docs/rules/no-dynamic-delete.md)                               | Bans usage of the delete operator with computed key expressions.                                                                                    |                    |          |                   |
 | [`@typescript-eslint/no-empty-function`](./docs/rules/no-empty-function.md)                               | Disallow empty functions                                                                                                                            | :heavy_check_mark: |          |                   |
 | [`@typescript-eslint/no-empty-interface`](./docs/rules/no-empty-interface.md)                             | Disallow the declaration of empty interfaces                                                                                                        | :heavy_check_mark: |          |                   |
 | [`@typescript-eslint/no-explicit-any`](./docs/rules/no-explicit-any.md)                                   | Disallow usage of the `any` type                                                                                                                    | :heavy_check_mark: | :wrench: |                   |

diff --git a/packages/eslint-plugin/docs/rules/no-dynamic-delete.md b/packages/eslint-plugin/docs/rules/no-dynamic-delete.md
@@ -0,0 +1,27 @@
+# no-dynamic-delete
+
+Bans usage of the delete operator with computed key expressions.
+
+## Rule Details
+
+Deleting dynamically computed keys is dangerous and not well optimized.
+
+Also consider using a `Map` or `Set` if you’re storing collections of objects. Using
+`Object`s can cause occasional edge case bugs, such as if a key is named “hasOwnProperty”.
+
+### Options
+
+Not configurable
+
+## When Not To Use It
+
+If you require deleting computed object property keys, consider
+setting the property value to `undefined` instead, or creating a new
+object without the property you wish to delete.
+
+If those alternatives do not work for you, you should use `delete` and
+disable this rule.
+
+## Related to
+
+- TSLint: [`no-dynamic-delete`](https://palantir.github.io/tslint/rules/no-dynamic-delete/)
diff --git a/packages/eslint-plugin/src/configs/all.json b/packages/eslint-plugin/src/configs/all.json
@@ -26,6 +26,7 @@
     "@typescript-eslint/member-ordering": "error",
     "no-array-constructor": "off",
     "@typescript-eslint/no-array-constructor": "error",
+    "@typescript-eslint/no-dynamic-delete": "error",
     "no-empty-function": "off",
     "@typescript-eslint/no-empty-function": "error",
     "@typescript-eslint/no-empty-interface": "error",

diff --git a/packages/eslint-plugin/src/rules/index.ts b/packages/eslint-plugin/src/rules/index.ts
@@ -62,6 +62,7 @@ import typedef from './typedef';
 import unboundMethod from './unbound-method';
 import unifiedSignatures from './unified-signatures';
 import useDefaultTypeParameter from './no-unnecessary-type-arguments';
+import noDynamicDelete from './no-dynamic-delete';
 
 export default {
   'adjacent-overload-signatures': adjacentOverloadSignatures,
@@ -84,6 +85,7 @@ export default {
   'member-naming': memberNaming,
   'member-ordering': memberOrdering,
   'no-array-constructor': noArrayConstructor,
+  'no-dynamic-delete': noDynamicDelete,
   'no-empty-function': noEmptyFunction,
   'no-empty-interface': noEmptyInterface,
   'no-explicit-any': noExplicitAny,

diff --git a/packages/eslint-plugin/src/rules/no-dynamic-delete.ts b/packages/eslint-plugin/src/rules/no-dynamic-delete.ts
@@ -0,0 +1,37 @@
+import { TSESTree } from '@typescript-eslint/experimental-utils';
+import * as util from '../util';
+
+export default util.createRule({
+  name: 'no-dynamic-delete',
+  meta: {
+    type: 'problem',
+    docs: {
+      description:
+        'Bans usage of the delete operator with computed key expressions.',
+      category: 'Possible Errors',
+      recommended: false,
+      requiresTypeChecking: false,
+    },
+    messages: {
+      noDynamicDelete: 'Do not delete dynamically computed property keys.',
+    },
+    schema: [],
+  },
+  defaultOptions: [null],
-  defaultOptions: [null],
+  defaultOptions: [],
-  defaultOptions: [null],
+  defaultOptions: [],
+  create(context) {
+    return {
+      UnaryExpression(node: TSESTree.UnaryExpression): void {
+        if (node.operator !== 'delete') {
+          return;
+        }
+
+        if ((node.argument as TSESTree.MemberExpression).computed) {
-        if ((node.argument as TSESTree.MemberExpression).computed) {
+        if (node.argument.type === TSESTree.MemberExpression && node.argument.computed) {
-        if ((node.argument as TSESTree.MemberExpression).computed) {
+        if (node.argument.type === TSESTree.MemberExpression && node.argument.computed) {
+          context.report({
+            node,
+            messageId: 'noDynamicDelete',
+          });
+        }
+      },
+    };
+  },
+});
diff --git a/packages/eslint-plugin/tests/rules/no-dynamic-delete.test.ts b/packages/eslint-plugin/tests/rules/no-dynamic-delete.test.ts
@@ -0,0 +1,77 @@
+import rule from '../../src/rules/no-dynamic-delete';
+import { RuleTester } from '../RuleTester';
+
+const ruleTester = new RuleTester({
+  parser: '@typescript-eslint/parser',
+});
+
+const messageId = 'noDynamicDelete';
+
+ruleTester.run('no-dynamic-delete', rule, {
+  valid: [
+    {
+      code: 'delete container.a;',
+    },
+    {
+      code: 'delete container.b;',
+    },
+  ],
+  invalid: [
+    {
+      code: 'delete container["a" + "b"];',
+      errors: [
+        {
+          messageId,
+        },
+      ],
+    },
+    {
+      code: 'delete container["c"]',
+      errors: [
+        {
+          messageId,
+        },
+      ],
+    },
+    {
+      code: 'delete container[7]',
+      errors: [
+        {
+          messageId,
+        },
+      ],
+    },
+    {
+      code: 'delete container[+7]',
+      errors: [
+        {
+          messageId,
+        },
+      ],
+    },
+    {
+      code: 'delete container[-7]',
+      errors: [
+        {
+          messageId,
+        },
+      ],
+    },
+    {
+      code: 'delete container[NaN]',
+      errors: [
+        {
+          messageId,
+        },
+      ],
+    },
+    {
+      code: 'delete container[getComputedName()]',
+      errors: [
+        {
+          messageId,
+        },
+      ],
+    },
+  ],
+});