Rename classes utility function to joinClasses in order to reduce naming confusion

core/src/jsMain/kotlin/dev/fritz2/core/foundation.kt

@@ -119,8 +119,39 @@ fun addGlobalStyles(css: List<String>) {
  * Joins all given [classes] strings to one html-class-attribute [String]
  * by filtering all out which are null or blank.
  */
-fun classes(vararg classes: String?): String =
-    classes.filter { !it.isNullOrBlank() }.joinToString(" ")
+@Deprecated("Use joinClassNames instead.", ReplaceWith("joinClasses(*classes)"))
+fun classes(vararg classes: String?): String = joinClasses(*classes)
+
+/**
+ * Joins all given [classes] strings to one html-class-attribute [String].
+ * Individual Strings that are null or blank are filtered out.
+ *
+ * __Examples__
+ *
+ * ```
+ * val classes = joinClasses(
+ *     "class1",
+ *     null,
+ *     "class2",
+ *     ""
+ * )
+ * println(classes) // prints "class1 class2"
+ * ```
+ *
+ * Using this function, it is also possible to conditionally construct classes strings without having
+ * to do dangerous string concatenation:
+ *
+ * ```
+ * val classes = joinClasses(
+ *    "class1",
+ *    "class2".takeIf { it.length > 10 }
+ * )
+ *
+ * println(classes) // prints "class1"
+ * ```
+ */
+fun joinClasses(vararg classes: String?): String =
+    classes.filterNot(String?::isNullOrBlank).joinToString(separator = " ")
 
 /**
  * Helper function to call a native js function with concrete return type [T]

core/src/jsMain/kotlin/dev/fritz2/core/tags.kt

@@ -376,7 +376,9 @@ open class HtmlTag<out E : Element>(
     private val classesStateFlow by lazy {
         MutableStateFlow<List<StateFlow<String>>>(listOfNotNull(baseClass?.let { MutableStateFlow(it) }))
             .also { classesFlowList ->
-                attr("class", classesFlowList.flatMapLatest { styleFlows -> combine(styleFlows) { classes(*it) } })
+                attr("class", classesFlowList.flatMapLatest { styleFlows ->
+                    combine(styleFlows) { joinClasses(*it) }
+                })
             }
     }
 
@@ -386,7 +388,7 @@ open class HtmlTag<out E : Element>(
      * This function is used to create the initial class name values to be applied immediately
      * to the domnode.
      */
-    private fun buildClasses() = classes(*classesStateFlow.value.map { it.value }.toTypedArray())
+    private fun buildClasses() = joinClasses(*classesStateFlow.value.map { it.value }.toTypedArray())
 
     override fun className(value: String) {
         classesStateFlow.value += MutableStateFlow(value)

core/src/jsMain/kotlin/dev/fritz2/core/transitions.kt

@@ -60,12 +60,12 @@ class Transition(
             val transition = payload.unsafeCast<Transition?>()
             if (transition?.enter != null) {
                 val classes = target.domNode.getAttribute("class").orEmpty()
-                target.domNode.setAttribute("class", classes(classes, transition.enterStart))
+                target.domNode.setAttribute("class", joinClasses(classes, transition.enterStart))
                 kotlinx.browser.window.awaitAnimationFrame()
                 kotlinx.browser.window.awaitAnimationFrame()
                 target.domNode.setAttribute(
                     "class",
-                    classes(classes, transition.enter, transition.enterEnd)
+                    joinClasses(classes, transition.enter, transition.enterEnd)
                 )
                 target.waitForAnimation()
                 target.domNode.setAttribute("class", classes)
@@ -144,14 +144,14 @@ fun Tag<HTMLElement>.transition(on: Flow<Boolean>, transition: Transition) {
             emit(transition.enterStart.orEmpty())
             kotlinx.browser.window.awaitAnimationFrame()
             kotlinx.browser.window.awaitAnimationFrame()
-            emit(classes(transition.enter, transition.enterEnd))
+            emit(joinClasses(transition.enter, transition.enterEnd))
             waitForAnimation()
             emit("")
         } else {
-            emit(classes(transition.leaveStart))
+            emit(joinClasses(transition.leaveStart))
             kotlinx.browser.window.awaitAnimationFrame()
             kotlinx.browser.window.awaitAnimationFrame()
-            emit(classes(transition.leave, transition.leaveEnd))
+            emit(joinClasses(transition.leave, transition.leaveEnd))
             waitForAnimation()
             emit("")
         }

examples/tictactoe/src/jsMain/kotlin/dev/fritz2/examples/tictactoe/tictactoe.kt

@@ -61,7 +61,7 @@ fun main() {
                 div("row") {
                     gameStore.field.renderEach { cell ->
                         div(
-                            classes(
+                            joinClasses(
                                 "col-4 border d-flex justify-content-center align-items-center",
                                 if (cell.isInWinningGroup) "bg-success" else "bg-white"
                             )

headless-demo/src/jsMain/kotlin/dev/fritz2/headlessdemo/components/dataCollection.kt

@@ -247,7 +247,7 @@ fun RenderContext.gridListDemo(amount: Int) {
                         tag = RenderContext::li
                     ) {
                         className(selected.combine(active) { sel, act ->
-                            classes(
+                            joinClasses(
                                 if (act) "ring-4 ring-primary-600" else "",
                                 if (sel) "bg-primary-700 text-primary-100" else "bg-primary-200 text-primary-900"
                             )

headless-demo/src/jsMain/kotlin/dev/fritz2/headlessdemo/components/inputField.kt

@@ -23,13 +23,13 @@ fun RenderContext.inputFieldDemo() {
                         | disabled:opacity-50""".trimMargin()
                 ) {
                     className(value.hasError.map {
-                        if (it) classes(
+                        if (it) joinClasses(
                             """border border-error-600 
                                 | text-error-800 placeholder:text-error-400
                                 | hover:border-error-800  
                                 | focus:outline-none focus:ring-4 focus:ring-error-600 focus:border-error-800""".trimMargin()
                         )
-                        else classes(
+                        else joinClasses(
                             """border border-primary-600 
                                 | text-primary-800 placeholder:text-slate-400
                                 | hover:border-primary-800  

headless-demo/src/jsMain/kotlin/dev/fritz2/headlessdemo/components/textArea.kt

@@ -1,7 +1,7 @@
 package dev.fritz2.headlessdemo.components
 
 import dev.fritz2.core.RenderContext
-import dev.fritz2.core.classes
+import dev.fritz2.core.joinClasses
 import dev.fritz2.core.placeholder
 import dev.fritz2.core.storeOf
 import dev.fritz2.headless.components.textArea
@@ -28,13 +28,13 @@ fun RenderContext.textAreaDemo() {
                         | disabled:opacity-50""".trimMargin()
                 ) {
                     className(value.hasError.map {
-                        if (it) classes(
+                        if (it) joinClasses(
                             """border border-error-600 
                                 | text-error-800 placeholder:text-error-400
                                 | hover:border-error-800  
                                 | focus:outline-none focus:ring-4 focus:ring-error-600 focus:border-error-800""".trimMargin()
                         )
-                        else classes(
+                        else joinClasses(
                             """border border-primary-600 
                                 | text-primary-800 placeholder:text-slate-400
                                 | hover:border-primary-800  

headless/src/jsMain/kotlin/dev/fritz2/headless/components/dataCollection.kt

@@ -463,7 +463,7 @@ class DataCollection<T, C : HTMLElement>(tag: Tag<C>) : Tag<C> by tag {
 
             return tag(
                 this,
-                if (selection.isSet) classes(classes, "cursor-pointer") else classes,
+                if (selection.isSet) joinClasses(classes, "cursor-pointer") else classes,
                 itemId,
                 scope
             ) {

headless/src/jsMain/kotlin/dev/fritz2/headless/components/listbox.kt

@@ -425,7 +425,7 @@ fun <T, C : HTMLElement> RenderContext.listbox(
     initialize: Listbox<T, C>.() -> Unit
 ): Tag<C> {
     addComponentStructureInfo(Listbox.COMPONENT_NAME, [email protected], this)
-    return tag(this, classes(classes, "relative"), id, scope) {
+    return tag(this, joinClasses(classes, "relative"), id, scope) {
         Listbox<T, C>(this, id).run {
             initialize(this)
             render()

headless/src/jsMain/kotlin/dev/fritz2/headless/components/menu.kt

@@ -327,7 +327,7 @@ fun <C : HTMLElement> RenderContext.menu(
     initialize: Menu<C>.() -> Unit
 ): Tag<C> {
     addComponentStructureInfo("menu", [email protected], this)
-    return tag(this, classes(classes, "relative"), id, scope) {
+    return tag(this, joinClasses(classes, "relative"), id, scope) {
         Menu(this, id).run {
             initialize(this)
             render()

headless/src/jsMain/kotlin/dev/fritz2/headless/components/popOver.kt

@@ -151,7 +151,7 @@ fun <C : HTMLElement> RenderContext.popOver(
     initialize: PopOver<C>.() -> Unit
 ): Tag<C> {
     addComponentStructureInfo("popOver", [email protected], this)
-    return tag(this, classes(classes, PopUpPanel.POPUP_RELATIVE), id, scope) {
+    return tag(this, joinClasses(classes, PopUpPanel.POPUP_RELATIVE), id, scope) {
         PopOver(this, id).run {
             initialize(this)
             render()

headless/src/jsMain/kotlin/dev/fritz2/headless/foundation/PopUpPanel.kt

@@ -267,7 +267,7 @@ abstract class PopUpPanel<C : HTMLElement>(
      * @param offset the distance between the reference element and the panel in pixels. Defaults to `5`
      */
     fun arrow(size: String = "popup-arrow-default", offset: Int = 5) {
-        div(classes(size, "popup-arrow")) {
+        div(joinClasses(size, "popup-arrow")) {
             arrow = this
             addMiddleware(offset(offset))
             addMiddleware(arrow { element = domNode })

www/src/pages/headless/radioGroup.md

@@ -109,8 +109,8 @@ radioGroup<HTMLFieldSetElement, Plan?>(tag = RenderContext::fieldset) {
             radioGroupOptionToggle {
                 // combine `selected` and `active`-Flow with `className` to react to state changes
                 className(selected.combine(active) { sel, act ->
-                    // use `classes` to attach both styling results
-                    classes(
+                    // use `joinClasses` to attach both styling results
+                    joinClasses(
                         if (sel) "bg-indigo-200" else "bg-white",
                         if (act) "ring-2 ring-indigo-500 border-transparent" else "border-gray-300"
                     )

www/src/pages/headless/tabGroup.md

@@ -114,8 +114,8 @@ tabGroup {
             tab {
                 // combine `selected` and `active`-Flow with `className` to react to state changes
                 className(selected.combine(active) { sel, act ->
-                    // use `classes` to attach both styling results
-                    classes(
+                    // use `joinClasses` to attach both styling results
+                    joinClasses(
                         if (sel == index) "bg-primary-800 text-white shadow-md"
                         else "text-primary-100 hover:bg-primary-900/[0.12]",
                         if (act) "ring-2 ring-white border-transparent" 

www/src/pages/headless/toast.md

@@ -104,7 +104,7 @@ toast("default") {
 
     button {
         icon(
-            classes = "w-4 h-4 text-primary-900",
+            joinClasses = "w-4 h-4 text-primary-900",
             content = HeroIcons.x
         )
         clicks handledBy close // call close handler