diff --git a/js/js.libraries/src/core/collections/ArrayList.kt b/js/js.libraries/src/core/collections/ArrayList.kt
index ea36b6ec489..c46864f5927 100644
--- a/js/js.libraries/src/core/collections/ArrayList.kt
+++ b/js/js.libraries/src/core/collections/ArrayList.kt
@@ -21,6 +21,10 @@ public open class ArrayList<E> internal constructor(private var array: Array<Any
     public constructor(capacity: Int = 0) : this(emptyArray()) {}
     public constructor(elements: Collection<E>) : this(elements.toTypedArray<Any?>()) {}
 
+    /** Does nothing in this ArrayList implementation. */
+    public fun trimToSize() {}
+    /** Does nothing in this ArrayList implementation. */
+    public fun ensureCapacity(minCapacity: Int) {}
 
     override val size: Int get() = array.size
     override fun get(index: Int): E = array[rangeCheck(index)] as E
diff --git a/libraries/stdlib/test/js/JsCollectionsTest.kt b/libraries/stdlib/test/js/JsCollectionsTest.kt
index fdf935b8009..47202349807 100644
--- a/libraries/stdlib/test/js/JsCollectionsTest.kt
+++ b/libraries/stdlib/test/js/JsCollectionsTest.kt
@@ -37,6 +37,13 @@ class JsCollectionsTest {
         snapshotDoesNotCreateView(arrayOf<Any>("first", "last"), { arrayListOf(*it) })
     }
 
+    @test fun arrayListCapacity() {
+        val list = ArrayList<Any>(20)
+        list.ensureCapacity(100)
+        list.trimToSize()
+        assertTrue(list.isEmpty())
+    }
+
     @test fun listEqualsOperatesOnAny() {
         assertFalse(listOf(1, 2, 3).equals(object {}))
     }