feat: support TS syntax in init-declarations (#19540)

snitin315 · web-flow · commit 72650acdb715 · 2025-03-31T10:46:12.000-04:00
* feat: support TS syntax in `init-declarations`

* chore: fix lint

* chore: fix formatting

* chore: refactor code

* chore: refactor code

* chore: fix lint

* test: add more cases
diff --git a/docs/src/rules/init-declarations.md b/docs/src/rules/init-declarations.md
@@ -146,6 +146,98 @@ for (let i = 0; i < 1; i++) {}
 
 :::
 
+This rule additionally supports TypeScript type syntax.
+
+Examples of **incorrect** TypeScript code for this rule:
+
+::: incorrect
+
+```ts
+/* eslint init-declarations: ["error", "never"] */
+
+let arr: string[] = ['arr', 'ar'];
+
+const class1 = class NAME {
+	constructor() {
+	  var name1: string = 'hello';
+	}
+};
+
+namespace myLib {
+	let numberOfGreetings: number = 2;
+}
+
+```
+
+:::
+
+::: incorrect
+
+```ts
+/* eslint init-declarations: ["error", "always"] */
+
+namespace myLib {
+	let numberOfGreetings: number;
+}
+
+namespace myLib1 {
+	const foo: number;
+	namespace myLib2 {
+	  let bar: string;
+	  namespace myLib3 {
+		let baz: object;
+	  }
+	}
+}
+
+```
+
+:::
+
+Examples of **correct** TypeScript code for this rule:
+
+::: correct
+
+```ts
+/* eslint init-declarations: ["error", "never"] */
+
+declare const foo: number;
+
+declare namespace myLib {
+	let numberOfGreetings: number;
+}
+
+interface GreetingSettings {
+	greeting: string;
+	duration?: number;
+	color?: string;
+}
+```
+
+:::
+
+::: correct
+
+```ts
+/* eslint init-declarations: ["error", "always"] */
+
+declare const foo: number;
+
+declare namespace myLib {
+	let numberOfGreetings: number;
+}
+
+interface GreetingSettings {
+	greeting: string;
+	duration?: number;
+	color?: string;
+}
+
+```
+
+:::
+
+
 ## When Not To Use It
 
 When you are indifferent as to how your variables are initialized.
diff --git a/lib/rules/init-declarations.js b/lib/rules/init-declarations.js
@@ -48,6 +48,8 @@ function isInitialized(node) {
 module.exports = {
 	meta: {
 		type: "suggestion",
+		dialects: ["typescript", "javascript"],
+		language: "javascript",
 
 		docs: {
 			description:
@@ -105,15 +107,34 @@ module.exports = {
 		const mode = context.options[0] || MODE_ALWAYS;
 		const params = context.options[1] || {};
 
+		// Track whether we're inside a declared namespace
+		let insideDeclaredNamespace = false;
+
 		//--------------------------------------------------------------------------
 		// Public API
 		//--------------------------------------------------------------------------
 
 		return {
+			TSModuleDeclaration(node) {
+				if (node.declare) {
+					insideDeclaredNamespace = true;
+				}
+			},
+
+			"TSModuleDeclaration:exit"(node) {
+				if (node.declare) {
+					insideDeclaredNamespace = false;
+				}
+			},
+
 			"VariableDeclaration:exit"(node) {
 				const kind = node.kind,
 					declarations = node.declarations;
 
+				if (node.declare || insideDeclaredNamespace) {
+					return;
+				}
+
 				for (let i = 0; i < declarations.length; ++i) {
 					const declaration = declarations[i],
 						id = declaration.id,
diff --git a/tests/lib/rules/init-declarations.js b/tests/lib/rules/init-declarations.js
