diff --git a/libraries/stdlib/api/js-v1/kotlin.text.kt b/libraries/stdlib/api/js-v1/kotlin.text.kt
index 607a2a72950..3510921a03f 100644
--- a/libraries/stdlib/api/js-v1/kotlin.text.kt
+++ b/libraries/stdlib/api/js-v1/kotlin.text.kt
@@ -1275,8 +1275,8 @@ public final class StringBuilder : kotlin.text.Appendable, kotlin.CharSequence {
     @kotlin.WasExperimental(markerClass = {kotlin.ExperimentalStdlibApi::class})
     public final fun appendRange(value: kotlin.CharSequence, startIndex: kotlin.Int, endIndex: kotlin.Int): kotlin.text.StringBuilder
 
-    @kotlin.SinceKotlin(version = "1.4")
-    @kotlin.WasExperimental(markerClass = {kotlin.ExperimentalStdlibApi::class})
+    @kotlin.SinceKotlin(version = "1.3")
+    @kotlin.Deprecated(level = DeprecationLevel.ERROR, message = "Obtaining StringBuilder capacity is not supported in JS and common code.")
     public final fun capacity(): kotlin.Int
 
     @kotlin.SinceKotlin(version = "1.3")
diff --git a/libraries/stdlib/api/js/kotlin.text.kt b/libraries/stdlib/api/js/kotlin.text.kt
index 607a2a72950..3510921a03f 100644
--- a/libraries/stdlib/api/js/kotlin.text.kt
+++ b/libraries/stdlib/api/js/kotlin.text.kt
@@ -1275,8 +1275,8 @@ public final class StringBuilder : kotlin.text.Appendable, kotlin.CharSequence {
     @kotlin.WasExperimental(markerClass = {kotlin.ExperimentalStdlibApi::class})
     public final fun appendRange(value: kotlin.CharSequence, startIndex: kotlin.Int, endIndex: kotlin.Int): kotlin.text.StringBuilder
 
-    @kotlin.SinceKotlin(version = "1.4")
-    @kotlin.WasExperimental(markerClass = {kotlin.ExperimentalStdlibApi::class})
+    @kotlin.SinceKotlin(version = "1.3")
+    @kotlin.Deprecated(level = DeprecationLevel.ERROR, message = "Obtaining StringBuilder capacity is not supported in JS and common code.")
     public final fun capacity(): kotlin.Int
 
     @kotlin.SinceKotlin(version = "1.3")
diff --git a/libraries/stdlib/js/src/kotlin/text/StringBuilderJs.kt b/libraries/stdlib/js/src/kotlin/text/StringBuilderJs.kt
index 28e72acd311..f8e6d95dfbf 100644
--- a/libraries/stdlib/js/src/kotlin/text/StringBuilderJs.kt
+++ b/libraries/stdlib/js/src/kotlin/text/StringBuilderJs.kt
@@ -17,7 +17,6 @@ public actual class StringBuilder actual constructor(content: String) : Appendab
      * In Kotlin/JS implementation of StringBuilder the initial capacity has no effect on the further performance of operations.
      */
     actual constructor(capacity: Int) : this() {
-        this.asDynamic()._capacity = capacity
     }
 
     /** Constructs a string builder that contains the same characters as the specified [content] char sequence. */
@@ -135,9 +134,10 @@ public actual class StringBuilder actual constructor(content: String) : Appendab
      *
      * In Kotlin/JS implementation of StringBuilder the value returned from this method may not indicate the actual size of the backing storage.
      */
-    @SinceKotlin("1.4")
-    @WasExperimental(ExperimentalStdlibApi::class)
-    actual fun capacity(): Int = if (this.asDynamic()._capacity !== undefined) maxOf(this.asDynamic()._capacity, length) else length
+    @SinceKotlin("1.3")
+//    @ExperimentalStdlibApi
+    @Deprecated("Obtaining StringBuilder capacity is not supported in JS and common code.", level = DeprecationLevel.ERROR)
+    actual fun capacity(): Int = length
 
     /**
      * Ensures that the capacity of this string builder is at least equal to the specified [minimumCapacity].
@@ -151,9 +151,6 @@ public actual class StringBuilder actual constructor(content: String) : Appendab
     @SinceKotlin("1.4")
     @WasExperimental(ExperimentalStdlibApi::class)
     actual fun ensureCapacity(minimumCapacity: Int) {
-        if (minimumCapacity > capacity()) {
-            this.asDynamic()._capacity = minimumCapacity
-        }
     }
 
     /**
@@ -367,9 +364,6 @@ public actual class StringBuilder actual constructor(content: String) : Appendab
     @SinceKotlin("1.4")
     @WasExperimental(ExperimentalStdlibApi::class)
     actual fun trimToSize() {
-        if (this.asDynamic()._capacity !== undefined) {
-            this.asDynamic()._capacity = length
-        }
     }
 
     override fun toString(): String = string
diff --git a/libraries/stdlib/src/kotlin/text/StringBuilder.kt b/libraries/stdlib/src/kotlin/text/StringBuilder.kt
index 66cf873a1d1..49a6c2b0332 100644
--- a/libraries/stdlib/src/kotlin/text/StringBuilder.kt
+++ b/libraries/stdlib/src/kotlin/text/StringBuilder.kt
@@ -90,8 +90,9 @@ expect class StringBuilder : Appendable, CharSequence {
      *
      * The capacity is the maximum length this string builder can have before an allocation occurs.
      */
-    @SinceKotlin("1.4")
-    @WasExperimental(ExperimentalStdlibApi::class)
+    @SinceKotlin("1.3")
+//    @ExperimentalStdlibApi
+    @Deprecated("Obtaining StringBuilder capacity is not supported in JS and common code.", level = DeprecationLevel.ERROR)
     fun capacity(): Int
 
     /**
diff --git a/libraries/stdlib/test/text/StringBuilderTest.kt b/libraries/stdlib/test/text/StringBuilderTest.kt
index 408689fe085..991b7875de8 100644
--- a/libraries/stdlib/test/text/StringBuilderTest.kt
+++ b/libraries/stdlib/test/text/StringBuilderTest.kt
@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2018 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
  * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
  */
 
@@ -236,8 +236,9 @@ class StringBuilderTest {
     }
 
     @Test
+    @Suppress("DEPRECATION_ERROR")
     fun capacityTest() {
-        assertEquals(100, StringBuilder(100).capacity())
+//        assertEquals(100, StringBuilder(100).capacity()) // not implemented in JS
 
         StringBuilder("string builder from string capacity test").let { sb ->
             assertTrue(sb.capacity() >= sb.length)
@@ -251,7 +252,7 @@ class StringBuilderTest {
             sb.ensureCapacity(1)
             assertTrue(sb.capacity() >= sb.length)
             sb.ensureCapacity(sb.length * 10)
-            assertTrue(sb.capacity() >= sb.length * 10)
+//            assertTrue(sb.capacity() >= sb.length * 10) // not implemented in JS
         }
     }
 
@@ -423,11 +424,11 @@ class StringBuilderTest {
     fun trimToSize() {
         StringBuilder("my trimToSize test").let { sb ->
             assertEquals(18, sb.length)
-            assertTrue(sb.capacity() >= sb.length)
+//            assertTrue(sb.capacity() >= sb.length)
             sb.append('1')
             sb.trimToSize()
             assertEquals(19, sb.length)
-            assertTrue(sb.capacity() >= sb.length)
+//            assertTrue(sb.capacity() >= sb.length)
         }
     }