Allow using 'as const' for creating tuples for map.replace (#3344)

* Allow using 'as const' for creating tuples for map.replace * add changeset Signed-off-by: Sebastian Malton <sebastian@malton.name> * Update tests Signed-off-by: Sebastian Malton <sebastian@malton.name>
mobxjs · Jul 19, 2022 · b375535 · b375535
1 parent 1581f14
commit b375535
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Showing 3 changed files with 24 additions and 2 deletions.
diff --git a/.changeset/clean-boats-repeat.md b/.changeset/clean-boats-repeat.md
@@ -0,0 +1,5 @@
+---
+"mobx": patch
+---
+
+Allow readonly tuples as part of IObservableMapInitialValues
diff --git a/packages/mobx/__tests__/v5/base/typescript-tests.ts b/packages/mobx/__tests__/v5/base/typescript-tests.ts
@@ -1887,6 +1887,21 @@ test("flow support throwing async generators", async () => {
     }
 })
 
+test("allow 'as const' for creating tuples for map.replace()", () => {
+    const map = mobx.observable.map<string, number>()
+    const srcValues = mobx.observable.array<string>()
+    const newValues = Array.from(srcValues, (value, index) => [value, index] as const)
+
+    map.replace(newValues)
+})
+
+test("allow 'as const' for creating tuples for observable.map()", () => {
+    const srcValues = mobx.observable.array<string>()
+    const newValues = Array.from(srcValues, (value, index) => [value, index] as const)
+
+    mobx.observable.map(newValues)
+})
+
 test("toJS bug #1413 (TS)", () => {
     class X {
         test = {

diff --git a/packages/mobx/src/types/observablemap.ts b/packages/mobx/src/types/observablemap.ts
@@ -43,7 +43,9 @@ export interface IKeyValueMap<V = any> {
 }
 
 export type IMapEntry<K = any, V = any> = [K, V]
+export type IReadonlyMapEntry<K = any, V = any> = readonly [K, V]
 export type IMapEntries<K = any, V = any> = IMapEntry<K, V>[]
+export type IReadonlyMapEntries<K = any, V = any> = IReadonlyMapEntry<K, V>[]
 
 export type IMapDidChange<K = any, V = any> = { observableKind: "map"; debugObjectName: string } & (
     | {
@@ -81,14 +83,14 @@ export const DELETE = "delete"
 
 export type IObservableMapInitialValues<K = any, V = any> =
     | IMapEntries<K, V>
+    | IReadonlyMapEntries<K, V>
     | IKeyValueMap<V>
     | Map<K, V>
 
 // just extend Map? See also https://gist.github.com/nestharus/13b4d74f2ef4a2f4357dbd3fc23c1e54
 // But: https://github.com/mobxjs/mobx/issues/1556
 export class ObservableMap<K = any, V = any>
-    implements Map<K, V>, IInterceptable<IMapWillChange<K, V>>, IListenable
-{
+    implements Map<K, V>, IInterceptable<IMapWillChange<K, V>>, IListenable {
     [$mobx] = ObservableMapMarker
     data_: Map<K, ObservableValue<V>>
     hasMap_: Map<K, ObservableValue<boolean>> // hasMap, not hashMap >-).