Simplify format() signature with MsgPath

README.md

@@ -69,16 +69,22 @@ The interfaces for
 will depend on the final MF2 data model.
 `MessageFormatOptions` contains configuration options
 for the creation of `MessageFormat` instances.
-The `Scope` object is used to lookup variable references used in the `Message`.
 The `ResolvedOptions` object contains the options
 resolved during the construction of the `MessageFormat` instance.
 
+The `msgPath` argument identifies the message from those available in the current resources.
+If all added resources share the same `id` value,
+the path may be given as a string or a string array.
+The `scope` argument is used to lookup variable references used in the `Message`.
+
 ```ts
 interface MessageFormatOptions {
  localeMatcher?: 'best fit' | 'lookup';
  ...
 }
 
+type MsgPath = string | string[] | { resId: string, path: string[] }
+
 type Scope = Record<string, unknown>
 
 interface Intl.MessageFormat {
@@ -90,14 +96,9 @@ interface Intl.MessageFormat {
 
  addResources(...resources: Resource[]);
 
- format(msgPath: string | string[], scope?: Scope): string;
- format(resId: string, msgPath: string | string[], scope?: Scope): string;
+ format(msgPath: MsgPath, scope?: Scope): string;
 
- formatToParts(
- resId: string,
- msgPath: string | string[],
- scope?: Scope
- ): MessageFormatPart[];
+ formatToParts(msgPath: MsgPath, scope?: Scope): MessageFormatPart[];
 
  resolvedOptions(): ResolvedOptions;
 }