fix #485 - forEach index

src/utils/ListCursor.js

@@ -522,7 +522,8 @@ export class ListCursor {
    */
   forEach (tr, f) {
     for (const val of this.values(tr)) {
-      f(val, this.index, this.type)
+      // decrease index because retrieving value will increase index
+      f(val, this.index - 1, this.type)
     }
   }
 
@@ -536,7 +537,7 @@ export class ListCursor {
     const arr = new Array(this.type._length - this.index)
     let i = 0
     for (const val of this.values(tr)) {
-      arr[i++] = f(val, this.index, this.type)
+      arr[i++] = f(val, this.index - 1, this.type)
     }
     return arr
   }

tests/y-array.tests.js

@@ -5,6 +5,21 @@ import * as t from 'lib0/testing'
 import * as prng from 'lib0/prng'
 import * as math from 'lib0/math'
 
+/**
+ * foreach has correct index - see yjs#485
+ *
+ * @param {t.TestCase} tc
+ */
+export const testArrayIndexIssue485 = tc => {
+  const doc = new Y.Doc()
+  const yarr = doc.getArray()
+  yarr.push([1, 2])
+  yarr.forEach((el, index) => {
+    t.info('index: ' + index)
+    t.assert(yarr.get(index) === el)
+  })
+}
+
 /**
  * @param {t.TestCase} tc
  */