Drop third argument of YAMLMap.prototype.toJS()

src/nodes/Pair.ts

@@ -35,7 +35,7 @@ export class Pair<
 
   toJS(doc: Document<DocValue>, ctx: ToJSContext): MapLike {
     const pair = ctx.mapAsMap ? new Map() : {}
-    addPairToJSMap(doc, ctx, pair, this, true)
+    addPairToJSMap(doc, ctx, pair, this)
     return pair
   }
 

src/nodes/Scalar.ts

@@ -76,8 +76,7 @@ export class Scalar<T = unknown> implements NodeBase {
     doc: Document<DocValue>,
     ctx: ToJSContext,
     map: MapLike,
-    value: unknown,
-    isPlainObject: boolean
+    value: unknown
   ) => void
 
   constructor(value: T) {

src/nodes/YAMLMap.ts

@@ -212,37 +212,15 @@ export class YAMLMap<
     return this
   }
 
-  /**
-   * A plain JavaScript representation of this node.
-   *
-   * @param Type - If set, forces the returned collection type
-   * @returns Instance of Type, Map, or Object
-   */
-  toJS<T extends MapLike = Map<any, any>>(
-    doc: Document<DocValue>,
-    ctx: ToJSContext | undefined,
-    Type: { new (): T }
-  ): T
-  toJS(doc: Document<DocValue>, ctx?: ToJSContext): any
-  toJS<T extends MapLike>(
+  /** A plain JavaScript representation of this node. */
+  toJS(
     doc: Document<DocValue>,
-    ctx?: ToJSContext,
-    Type?: { new (): T }
-  ) {
+    ctx?: ToJSContext
+  ): Map<any, any> | Record<any, any> {
     ctx ??= new ToJSContext()
-    let map: MapLike
-    let isPlainObject = false
-    if (Type) {
-      map = new Type()
-    } else if (ctx.mapAsMap) {
-      map = new Map()
-    } else {
-      map = {}
-      isPlainObject = true
-    }
+    const map = ctx.mapAsMap ? new Map() : {}
     if (this.anchor) ctx.setAnchor(this, map)
-    for (const pair of this.values.values())
-      addPairToJSMap(doc, ctx, map, pair, isPlainObject)
+    for (const pair of this.values.values()) addPairToJSMap(doc, ctx, map, pair)
     return map
   }
 

src/nodes/addPairToJSMap.ts

@@ -10,11 +10,10 @@ export function addPairToJSMap(
   doc: Document<DocValue>,
   ctx: ToJSContext,
   map: MapLike,
-  { key, value }: Pair,
-  isPlainObject: boolean
+  { key, value }: Pair
 ): void {
   if ('addToJSMap' in key && typeof key.addToJSMap === 'function') {
-    key.addToJSMap(doc, ctx, map, value, isPlainObject)
+    key.addToJSMap(doc, ctx, map, value)
   } else {
     const jsKey = key.toJS(doc, ctx)
     if (map instanceof Map) {
@@ -25,7 +24,7 @@ export function addPairToJSMap(
       const stringKey = stringifyKey(doc, ctx, key, jsKey)
       const jsValue = value ? value.toJS(doc, ctx) : value
       if (
-        (!isPlainObject && stringKey in map) ||
+        (map.constructor !== Object && stringKey in map) ||
         stringKey === '__proto__' ||
         stringKey === 'constructor'
       )

src/schema/yaml-1.1/merge.ts

@@ -46,26 +46,24 @@ function addToJSMap(
   doc: Document<DocValue>,
   ctx: ToJSContext,
   map: MapLike,
-  value: unknown,
-  isPlainObject: boolean
+  value: unknown
 ): void {
   const source = getMergeSource(doc, ctx, value)
   if (Array.isArray(source)) {
     for (const v of source) {
       const s = getMergeSource(doc, ctx, v)
-      mergeValue(doc, ctx, map, s, isPlainObject)
+      mergeValue(doc, ctx, map, s)
     }
   } else {
-    mergeValue(doc, ctx, map, source, isPlainObject)
+    mergeValue(doc, ctx, map, source)
   }
 }
 
 function mergeValue(
   doc: Document<DocValue>,
   ctx: ToJSContext,
   map: MapLike,
-  source: unknown,
-  isPlainObject: boolean
+  source: unknown
 ) {
   if (!(source instanceof YAMLMap))
     throw new Error('Merge sources must be maps or map aliases')
@@ -77,7 +75,11 @@ function mergeValue(
     } else if (map instanceof Set) {
       map.add(key)
     } else if (!Object.prototype.hasOwnProperty.call(map, key)) {
-      if (!isPlainObject || key === '__proto__' || key === 'constructor') {
+      if (
+        map.constructor !== Object ||
+        key === '__proto__' ||
+        key === 'constructor'
+      ) {
         Object.defineProperty(map, key, {
           value,
           writable: true,

tests/doc/types.ts

@@ -1113,11 +1113,9 @@ describe('custom tags', () => {
   class YAMLNullObject extends YAMLMap {
     tag: string = '!nullobject'
     toJS(doc: any, ctx?: any): any {
-      const obj = super.toJS<Record<any, any>>(
-        doc,
-        { ...ctx, mapAsMap: false },
-        Object
-      )
+      ctx = Object.create(ctx)
+      ctx.mapAsMap = false
+      const obj = super.toJS(doc, ctx)
       return Object.assign(Object.create(null), obj)
     }
   }