diff --git a/js/js.translator/testData/java/abstractList/cases/iterator.kt b/js/js.translator/testData/java/abstractList/cases/iterator.kt
index e7de9083a08..a5cb20cf7c0 100644
--- a/js/js.translator/testData/java/abstractList/cases/iterator.kt
+++ b/js/js.translator/testData/java/abstractList/cases/iterator.kt
@@ -4,7 +4,7 @@ import java.util.AbstractList
 
 class MyList<T>(vararg val data: T) : AbstractList<T>() {
     override fun get(index: Int) = data[index]
-    override fun size() = data.size()
+    override val size: Int get() = data.size()
 }
 
 fun test<T>(expected: String, list: List<T>) {
diff --git a/js/js.translator/testData/java/arrayList/cases/retainAll.kt b/js/js.translator/testData/java/arrayList/cases/retainAll.kt
index 76990dbb6e9..ea8042f7348 100644
--- a/js/js.translator/testData/java/arrayList/cases/retainAll.kt
+++ b/js/js.translator/testData/java/arrayList/cases/retainAll.kt
@@ -3,7 +3,7 @@ package foo
 import java.util.ArrayList;
 
 fun test<T>(a: List<T>, b: List<T>, removed: Boolean, expected: List<T>): String? {
-    val t = ArrayList<T>(a.size())
+    val t = ArrayList<T>(a.size)
     t.addAll(a)
 
     if (t.retainAll(b) != removed) return "$a.retainAll($b) != $removed, result list: $t"
diff --git a/js/js.translator/testData/kotlin_lib.js b/js/js.translator/testData/kotlin_lib.js
index 0fd49fc4918..c624cd32184 100644
--- a/js/js.translator/testData/kotlin_lib.js
+++ b/js/js.translator/testData/kotlin_lib.js
@@ -290,7 +290,7 @@
         /** @constructs */
         function (list, index) {
             this.list = list;
-            this.size = list.size();
+            this.size = list.size;
             this.index = (index === undefined) ? 0 : index;
         }, {
             hasNext: function () {
@@ -399,18 +399,18 @@
             return true;
         },
         isEmpty: function () {
-            return this.size() === 0;
+            return this.size === 0;
         },
         iterator: function () {
             // TODO: Do not implement mutable iterator() this way, make abstract
             return new Kotlin.ArrayIterator(this.toArray());
         },
         equals_za3rmp$: function (o) {
-            if (this.size() !== o.size()) return false;
+            if (this.size !== o.size) return false;
 
             var iterator1 = this.iterator();
             var iterator2 = o.iterator();
-            var i = this.size();
+            var i = this.size;
             while (i-- > 0) {
                 if (!Kotlin.equals(iterator1.next(), iterator2.next())) {
                     return false;
@@ -423,7 +423,7 @@
             var builder = "[";
             var iterator = this.iterator();
             var first = true;
-            var i = this.size();
+            var i = this.size;
             while (i-- > 0) {
                 if (first) {
                     first = false;
@@ -456,13 +456,13 @@
             return new Kotlin.ListIterator(this);
         },
         listIterator_za3lpa$: function(index) {
-            if (index < 0 || index > this.size()) {
-                throw new Kotlin.IndexOutOfBoundsException("Index: " + index + ", size: " + this.size());
+            if (index < 0 || index > this.size) {
+                throw new Kotlin.IndexOutOfBoundsException("Index: " + index + ", size: " + this.size);
             }
             return new Kotlin.ListIterator(this, index);
         },
         add_za3rmp$: function (element) {
-            this.add_vux3hl$(this.size(), element);
+            this.add_vux3hl$(this.size, element);
             return true;
         },
         addAll_9cca64$: function (index, collection) {
@@ -492,14 +492,14 @@
             return -1;
         },
         lastIndexOf_za3rmp$: function (o) {
-            var i = this.listIterator_za3lpa$(this.size());
+            var i = this.listIterator_za3lpa$(this.size);
             while (i.hasPrevious())
                 if (Kotlin.equals(i.previous(), o))
                     return i.nextIndex();
             return -1;
         },
         subList_vux9f0$: function(fromIndex, toIndex) {
-            if (fromIndex < 0 || toIndex > this.size())
+            if (fromIndex < 0 || toIndex > this.size)
                 throw new Kotlin.IndexOutOfBoundsException();
             if (fromIndex > toIndex)
                 throw new Kotlin.IllegalArgumentException();
@@ -533,11 +533,13 @@
                 this.checkRange(index);
                 this.list.set_vux3hl$(index + this.offset, value);
             },
-            size: function () {
-                return this._size;
+            size: {
+               get: function () {
+                   return this._size;
+               }
             },
             add_vux3hl$: function (index, element) {
-                if (index < 0 || index > this.size()) {
+                if (index < 0 || index > this.size) {
                     throw new Kotlin.IndexOutOfBoundsException();
                 }
                 this.list.add_vux3hl$(index + this.offset, element);
@@ -572,8 +574,10 @@
                 this.checkRange(index);
                 this.array[index] = value;
             },
-            size: function () {
-                return this.array.length;
+            size: {
+               get: function () {
+                   return this.array.length;
+               }
             },
             iterator: function () {
                 return Kotlin.arrayIterator(this.array);
@@ -587,7 +591,7 @@
             },
             addAll_4fm7v2$: function (collection) {
                 var it = collection.iterator();
-                for (var i = this.array.length, n = collection.size(); n-- > 0;) {
+                for (var i = this.array.length, n = collection.size; n-- > 0;) {
                     this.array[i++] = it.next();
                 }
             },
diff --git a/js/js.translator/testData/maps.js b/js/js.translator/testData/maps.js
index 95602409b56..d927d4471fb 100644
--- a/js/js.translator/testData/maps.js
+++ b/js/js.translator/testData/maps.js
@@ -61,7 +61,7 @@
     }
 
     function hashSetEquals(o) {
-        if (o == null || this.size() !== o.size()) return false;
+        if (o == null || this.size !== o.size) return false;
 
         return this.containsAll_4fm7v2$(o);
     }
@@ -399,13 +399,15 @@
             return oldValue;
         };
 
-        this.size = function () {
-            var total = 0, i = buckets.length;
-            while (i--) {
-                total += buckets[i].entries.length;
+        Object.defineProperty(this, "size", {
+            get: function () {
+                var total = 0, i = buckets.length;
+                while (i--) {
+                    total += buckets[i].entries.length;
+                }
+                return total;
             }
-            return total;
-        };
+        });
 
         this.each = function (callback) {
             var entries = that._entries(), i = entries.length, entry;
@@ -460,7 +462,7 @@
         };
 
         this.equals_za3rmp$ = function(o) {
-            if (o == null || this.size() !== o.size()) return false;
+            if (o == null || this.size !== o.size) return false;
 
             var entries = this._entries();
             var i = entries.length;
@@ -563,8 +565,10 @@
             isEmpty: function () {
                 return this.map.isEmpty();
             },
-            size: function () {
-                return this.map.size();
+            size: {
+                get: function () {
+                    return this.map.size;
+                }
             },
             contains_za3rmp$: function (o) {
                 return this.map.containsValue_za3rmp$(o);
@@ -585,8 +589,10 @@
             this.$size = 0;
             this.map = Object.create(null);
         }, {
-            size: function () {
-                return this.$size;
+            size: {
+                get: function () {
+                    return this.$size;
+                }
             },
             isEmpty: function () {
                 return this.$size === 0;
@@ -679,7 +685,7 @@
                 return builder + "}";
             },
             equals_za3rmp$: function(o) {
-                if (o == null || this.size() !== o.size()) return false;
+                if (o == null || this.size !== o.size) return false;
                 var map = this.map;
                 for (var key in map) {
                     var key_ = this.convertKeyToKeyType(key);
@@ -822,8 +828,10 @@
         {
             equals_za3rmp$: hashSetEquals,
             hashCode: hashSetHashCode,
-            size: function () {
-                return this.map.size()
+            size: {
+                get: function () {
+                    return this.map.size;
+                }
             },
             contains_za3rmp$: function (element) {
                 return this.map.containsKey_za3rmp$(element);
@@ -897,8 +905,10 @@
         {
             equals_za3rmp$: hashSetEquals,
             hashCode: hashSetHashCode,
-            size: function () {
-                return this.$size;
+            size: {
+                get: function () {
+                    return this.$size;
+                }
             },
             contains_za3rmp$: function (key) {
                 return this.map[key] === true;
@@ -1025,9 +1035,9 @@
             hashTable.clear();
         };
 
-        this.size = function () {
-            return hashTable.size();
-        };
+        Object.defineProperty(this, "size", { get: function () {
+            return hashTable.size;
+        }});
 
         this.isEmpty = function () {
             return hashTable.isEmpty();
diff --git a/libraries/stdlib/test/collections/IterableTests.kt b/libraries/stdlib/test/collections/IterableTests.kt
index c0bb24d4b58..62d3ca57a2c 100644
--- a/libraries/stdlib/test/collections/IterableTests.kt
+++ b/libraries/stdlib/test/collections/IterableTests.kt
@@ -142,7 +142,7 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
         val foo = data.filter { it.startsWith("f") }
         expect(true) { foo is List<String> }
         expect(true) { foo.all { it.startsWith("f") } }
-        expect(1) { foo.size() }
+        expect(1) { foo.size }
         assertEquals(listOf("foo"), foo)
     }
 
@@ -151,7 +151,7 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
         val foo = data.drop(1)
         expect(true) { foo is List<String> }
         expect(true) { foo.all { it.startsWith("b") } }
-        expect(1) { foo.size() }
+        expect(1) { foo.size }
         assertEquals(listOf("bar"), foo)
     }
 
@@ -160,7 +160,7 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
         val foo = data.dropWhile { it[0] == 'f' }
         expect(true) { foo is List<String> }
         expect(true) { foo.all { it.startsWith("b") } }
-        expect(1) { foo.size() }
+        expect(1) { foo.size }
         assertEquals(listOf("bar"), foo)
     }
 
@@ -169,7 +169,7 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
         val notFoo = data.filterNot { it.startsWith("f") }
         expect(true) { notFoo is List<String> }
         expect(true) { notFoo.none { it.startsWith("f") } }
-        expect(1) { notFoo.size() }
+        expect(1) { notFoo.size }
         assertEquals(listOf("bar"), notFoo)
     }
 
@@ -216,7 +216,7 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
         assertTrue {
             lengths.all { it == 3 }
         }
-        assertEquals(2, lengths.size())
+        assertEquals(2, lengths.size)
         assertEquals(listOf(3, 3), lengths)
     }
 
@@ -228,14 +228,14 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
     @Test
     fun mapIndexed() {
         val shortened = data.mapIndexed { index, value -> value.substring(0..index) }
-        assertEquals(2, shortened.size())
+        assertEquals(2, shortened.size)
         assertEquals(listOf("f", "ba"), shortened)
     }
 
     @Test
     fun withIndex() {
         val indexed = data.withIndex().map { it.value.substring(0..it.index) }
-        assertEquals(2, indexed.size())
+        assertEquals(2, indexed.size)
         assertEquals(listOf("f", "ba"), indexed)
     }