js visibility of objects extensions

coroutines/src/jsMain/kotlin/dev.inmo.micro_utils.coroutines/ElementVisibilityFlow.kt

@@ -0,0 +1,28 @@
+package dev.inmo.micro_utils.coroutines
+
+import dev.inmo.micro_utils.common.onRemoved
+import dev.inmo.micro_utils.common.onVisibilityChanged
+import kotlinx.coroutines.flow.*
+import org.w3c.dom.Element
+
+fun Element.visibilityFlow(): Flow<Boolean> = channelFlow {
+    var previousData: Boolean? = null
+
+    val observer = onVisibilityChanged { intersectionRatio, _ ->
+        val currentData = intersectionRatio > 0
+        if (currentData != previousData) {
+            trySend(currentData)
+        }
+        previousData = currentData
+    }
+
+    val removeObserver = onRemoved {
+        observer.disconnect()
+        close()
+    }
+
+    invokeOnClose {
+        observer.disconnect()
+        removeObserver.disconnect()
+    }
+}