Add optional iterable param to Y.Map(), matching Map()

src/types/YMap.js

@@ -45,13 +45,23 @@ export class YMapEvent extends YEvent {
  * @implements {Iterable<T>}
  */
 export class YMap extends AbstractType {
-  constructor () {
+  /**
+   *
+   * @param {Iterable<readonly [string, any]>=} entries - an optional iterable to initialize the YMap
+   */
+  constructor (entries) {
     super()
     /**
      * @type {Map<string,any>?}
      * @private
      */
-    this._prelimContent = new Map()
+    this._prelimContent = null
+
+    if (entries === undefined) {
+      this._prelimContent = new Map()
+    } else {
+      this._prelimContent = new Map(entries)
+    }
   }
 
   /**

tests/y-map.tests.js

@@ -8,6 +8,33 @@ import * as Y from '../src/index.js'
 import * as t from 'lib0/testing.js'
 import * as prng from 'lib0/prng.js'
 
+/**
+ * @param {t.TestCase} tc
+ */
+export const testMapHavingIterableAsConstructorParamTests = tc => {
+  const { map0 } = init(tc, { users: 1 })
+
+  const m1 = new Y.Map(Object.entries({ number: 1, string: 'hello' }))
+  map0.set('m1', m1)
+  t.assert(m1.get('number') === 1)
+  t.assert(m1.get('string') === 'hello')
+
+  const m2 = new Y.Map([
+    ['object', { x: 1 }],
+    ['boolean', true]
+  ])
+  map0.set('m2', m2)
+  t.assert(m2.get('object').x === 1)
+  t.assert(m2.get('boolean') === true)
+
+  const m3 = new Y.Map([...m1, ...m2])
+  map0.set('m3', m3)
+  t.assert(m3.get('number') === 1)
+  t.assert(m3.get('string') === 'hello')
+  t.assert(m3.get('object').x === 1)
+  t.assert(m3.get('boolean') === true)
+}
+
 /**
  * @param {t.TestCase} tc
  */