From f90c09bad74d025c4608a2b9dfd5c79d5079ca7c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Damian=20G=C5=82owala?= <damian.glowala.rebkow@gmail.com>
Date: Wed, 6 Dec 2023 13:04:57 +0100
Subject: [PATCH] feat(types): autocomplete `purpose` in IconResource (#616)

* types: autocomplete `purpose` in IconResource

* chore: fix string literal union

---------

Co-authored-by: userquin <userquin@gmail.com>
---
 src/types.ts | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/types.ts b/src/types.ts
index 9eaba499..9036235b 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -218,6 +218,15 @@ export type Display = 'fullscreen' | 'standalone' | 'minimal-ui' | 'browser'
 export type DisplayOverride = Display | 'window-controls-overlay'
 export type IconPurpose = 'monochrome' | 'maskable' | 'any'
 
+interface Nothing {}
+
+/**
+ * type StringLiteralUnion<'maskable'> = 'maskable' | string
+ * This has auto completion whereas `'maskable' | string` doesn't
+ * Adapted from https://github.com/microsoft/TypeScript/issues/29729
+ */
+export type StringLiteralUnion<T extends U, U = string> = T | (U & Nothing)
+
 /**
  * @see https://w3c.github.io/manifest/#manifest-image-resources
  */
@@ -228,7 +237,7 @@ export interface IconResource {
   /**
    * **NOTE**: string values for backward compatibility with the old type.
    */
-  purpose?: string | IconPurpose | IconPurpose[]
+  purpose?: StringLiteralUnion<IconPurpose> | IconPurpose[]
 }
 
 export interface ManifestOptions {