class(Name) attribute now appends rather than overwrites.

Fixes #60

core/src/main/scala/japgolly/scalajs/react/vdom/Builder.scala

@@ -5,10 +5,14 @@ import japgolly.scalajs.react.{ReactElement, ReactNode, React}
 
 private[vdom] final class Builder {
 
+  private[this] var className: js.UndefOr[js.Any] = js.undefined
   private[this] var props    = new js.Object
   private[this] var style    = new js.Object
   private[this] var children = new js.Array[ReactNode]()
 
+  def addClassName(n: js.Any): Unit =
+    className = className.fold(n)(m => s"$m $n")
+
   def appendChild(c: ReactNode): Unit =
     children.push(c)
 
@@ -21,9 +25,11 @@ private[vdom] final class Builder {
   @inline private[this] def set(o: js.Object, k: String, v: js.Any): Unit =
     o.asInstanceOf[js.Dynamic].updateDynamic(k)(v)
 
-  @inline private[this] def hasStyle = js.Object.keys(style).length != 0
+  @inline private[this] def hasStyle: Boolean =
+    js.Object.keys(style).length != 0
 
   def render(tag: String): ReactElement = {
+    className.foreach(set(props, "className", _))
     if (hasStyle)
       set(props, "style", style)
     React.createElement(tag, props, children: _*)

core/src/main/scala/japgolly/scalajs/react/vdom/Extra.scala

@@ -41,9 +41,12 @@ object Extra {
   }
 
   trait Attrs {
+    final val className     = ClassNameAttr
+    final val cls           = className
+    final val `class`       = className
+
     final val colSpan       = "colSpan".attr
     final val rowSpan       = "rowSpan".attr
-    final val className     = "className".attr // same as cls and `class`
     final val htmlFor       = "htmlFor".attr   // same as `for`
     final val ref           = "ref".attr
     final val key           = "key".attr
@@ -126,19 +129,22 @@ object Extra {
     final def compositeAttr[A](k: Attr, f: (A, List[A]) => A, e: => TagMod = EmptyTag) =
       new CompositeAttr(k, f, e)
 
-    final val classSwitch = compositeAttr[String](className, (h,t) => (h::t) mkString " ")
-
     final def classSet(ps: (String, Boolean)*): TagMod =
-      classSwitch(ps.map(p => if (p._2) Some(p._1) else None): _*)(stringAttrX)
+      classSetImpl(EmptyTag, ps)
 
     final def classSet1(a: String, ps: (String, Boolean)*): TagMod =
-      classSet(((a, true) +: ps):_*)
+      classSetImpl(cls_=(a), ps)
 
     final def classSetM(ps: Map[String, Boolean]): TagMod =
-      classSet(ps.toSeq: _*)
+      classSetImpl(EmptyTag, ps.toSeq)
 
     final def classSet1M(a: String, ps: Map[String, Boolean]): TagMod =
-      classSet1(a, ps.toSeq: _*)
+      classSetImpl(cls_=(a), ps.toSeq)
   }
 
+  @inline private[vdom] def cls_=(v:  String): TagMod =
+    ClassNameAttr.:=(v)(stringAttrX)
+
+  private[vdom] def classSetImpl(z: TagMod, ps: Seq[(String, Boolean)]): TagMod =
+    ps.foldLeft(z)((q, p) => if (p._2) q + cls_=(p._1) else q)
 }

core/src/main/scala/japgolly/scalajs/react/vdom/HtmlAttrs.scala

@@ -270,20 +270,20 @@ trait HtmlAttrs {
    *
    */
   final val xmlns = "xmlns".attr
-  /**
-   * This attribute is a space-separated list of the classes of the element.
-   * Classes allows CSS and Javascript to select and access specific elements
-   * via the class selectors or functions like the DOM method
-   * document.getElementsByClassName. You can use cls as an alias for this
-   * attribute so you don't have to backtick-escape this attribute.
-   *
-   * MDN
-   */
-  final val `class` = "className".attr
-  /**
-   * Shorthand for the `class` attribute
-   */
-  final val cls = `class`
+//  /**
+//   * This attribute is a space-separated list of the classes of the element.
+//   * Classes allows CSS and Javascript to select and access specific elements
+//   * via the class selectors or functions like the DOM method
+//   * document.getElementsByClassName. You can use cls as an alias for this
+//   * attribute so you don't have to backtick-escape this attribute.
+//   *
+//   * MDN
+//   */
+//  final val `class` = "className".attr
+//  /**
+//   * Shorthand for the `class` attribute
+//   */
+//  final val cls = `class`
   /**
    * This attribute participates in defining the language of the element, the
    * language that non-editable elements are written in or the language that

core/src/main/scala/japgolly/scalajs/react/vdom/Scalatags.scala

@@ -79,6 +79,13 @@ final case class Attr(name: String) {
   def :=[T](v: T)(implicit ev: AttrValue[T]): TagMod = AttrPair(this, v, ev)
 }
 
+object ClassNameAttr {
+  def :=[T](t: T)(implicit av: AttrValue[T]): TagMod = new TagMod {
+    override def applyTo(b: Builder): Unit =
+      av.apply(t, b.addClassName)
+  }
+}
+
 /**
  * Wraps up a CSS style in a value.
  */
@@ -110,10 +117,9 @@ private[vdom] object Scalatags {
   /**
    * An [[Attr]], it's associated value, and an [[AttrValue]] of the correct type
    */
-  case class AttrPair[T](a: Attr, v: T, ev: AttrValue[T]) extends TagMod {
-    override def applyTo(t: Builder): Unit = {
-      ev.apply(t, a, v)
-    }
+  case class AttrPair[T](a: Attr, t: T, av: AttrValue[T]) extends TagMod {
+    override def applyTo(b: Builder): Unit =
+      av.apply(t, b.addAttr(a.name, _))
   }
   /**
    * Used to specify how to handle a particular type [[T]] when it is used as
@@ -124,7 +130,7 @@ private[vdom] object Scalatags {
     "No AttrValue defined for type ${T}; scalatags does not know how to use ${T} as an attribute"
   )
   trait AttrValue[T]{
-    def apply(t: Builder, a: Attr, v: T): Unit
+    def apply(v: T, b: js.Any => Unit): Unit
   }
 
   /**
@@ -182,7 +188,7 @@ private[vdom] object Scalatags {
   }
 
   final class OptionalAttrValue[T[_], A](ot: Optional[T], v: AttrValue[A]) extends AttrValue[T[A]] {
-    override def apply(b: Builder, s: Attr, t: T[A]) = ot.foreach(t)(v(b, s, _))
+    override def apply(ta: T[A], b: js.Any => Unit): Unit = ot.foreach(ta)(v(_, b))
   }
 
   final class OptionalStyleValue[T[_], A](ot: Optional[T], v: StyleValue[A]) extends StyleValue[T[A]] {
@@ -211,8 +217,7 @@ private[vdom] object Scalatags {
   }
 
   final class GenericAttr[T](f: T => js.Any) extends AttrValue[T] {
-    def apply(t: Builder, a: Attr, v: T): Unit =
-      t.addAttr(a.name, f(v))
+    def apply(v: T, b: js.Any => Unit): Unit = b(f(v))
   }
   object GenericAttr {
     @inline def apply[T <% js.Any] = new GenericAttr[T](a => a)

doc/CHANGELOG-0.7.md

@@ -1,6 +1,8 @@
 # 0.7.1 ([commit log](https://github.com/japgolly/scalajs-react/compare/v0.7.0...v0.7.1))
 
 * Support custom tags, attributes and styles via `"string".react{Attr,Style,Tag}`.
+* The `class` attribute now gets some special treatment in that it appends rather than overwrites.
+  `<.div(^.cls := "a", ^.cls := "b")` is now the same as `<.div(^.cls := "a b")`.
 
 
 # 0.7.0 ([commit log](https://github.com/japgolly/scalajs-react/compare/v0.6.1...v0.7.0))

test/src/test/scala/japgolly/scalajs/react/CoreTest.scala

@@ -131,7 +131,7 @@ object CoreTest extends TestSuite {
 
         'attributeChaining - test(
           div(`class` := "thing lol", id := "cow"),
-          """<div class="thing lol" id="cow"></div>""")
+          """<div id="cow" class="thing lol"></div>""")
 
         'mixingAttributesStylesAndChildren - test(
           div(id := "cow", float.left, p("i am a cow")),
@@ -154,7 +154,7 @@ object CoreTest extends TestSuite {
 
         'applyChaining - test(
           a(tabIndex := 1, cls := "lol")(href := "boo", alt := "g"),
-          """<a tabindex="1" class="lol" href="boo" alt="g"></a>""")
+          """<a tabindex="1" href="boo" alt="g" class="lol"></a>""")
       }
 
       'customAttr  - test(div("accept".reactAttr := "yay"), """<div accept="yay"></div>""")
@@ -168,13 +168,19 @@ object CoreTest extends TestSuite {
         r((false, false)) shouldRender """<div>x</div>"""
         r((true,  false)) shouldRender """<div class="p1">x</div>"""
         r((false, true))  shouldRender """<div class="p2">x</div>"""
-        r((true,  true))  shouldRender """<div class="p1 p2">x</div>"""
+        r((true,  true))  shouldRender """<div class="p2 p1">x</div>"""
       }
       'hasMandatory {
         val r = ReactComponentB[Boolean]("C").render(p => div(classSet1("mmm", "ccc" -> p))("x")).build
         r(false) shouldRender """<div class="mmm">x</div>"""
         r(true)  shouldRender """<div class="mmm ccc">x</div>"""
       }
+      'appends {
+        val r = ReactComponentB[Boolean]("C").render(p =>
+          div(cls := "neat", classSet1("mmm", "ccc" -> p), cls := "slowclap", "x")).build
+        r(false) shouldRender """<div class="neat mmm slowclap">x</div>"""
+        r(true)  shouldRender """<div class="neat mmm ccc slowclap">x</div>"""
+      }
     }
 
     'props {

test/src/test/scala/japgolly/scalajs/react/PrefixedVdomTest.scala

@@ -131,7 +131,7 @@ object PrefixedVdomTest extends TestSuite {
 
         'attributeChaining - test(
           <.div(^.`class` := "thing lol", ^.id := "cow"),
-          """<div class="thing lol" id="cow"></div>""")
+          """<div id="cow" class="thing lol"></div>""")
 
         'mixingAttributesStylesAndChildren - test(
           <.div(^.id := "cow", ^.float.left, <.p("i am a cow")),
@@ -154,7 +154,7 @@ object PrefixedVdomTest extends TestSuite {
 
         'applyChaining - test(
           <.a(^.tabIndex := 1, ^.cls := "lol")(^.href := "boo", ^.alt := "g"),
-          """<a tabindex="1" class="lol" href="boo" alt="g"></a>""")
+          """<a tabindex="1" href="boo" alt="g" class="lol"></a>""")
       }
     }
 
@@ -164,13 +164,19 @@ object PrefixedVdomTest extends TestSuite {
         r((false, false)) shouldRender """<div>x</div>"""
         r((true,  false)) shouldRender """<div class="p1">x</div>"""
         r((false, true))  shouldRender """<div class="p2">x</div>"""
-        r((true,  true))  shouldRender """<div class="p1 p2">x</div>"""
+        r((true,  true))  shouldRender """<div class="p2 p1">x</div>"""
       }
       'hasMandatory {
         val r = ReactComponentB[Boolean]("C").render(p => <.div(^.classSet1("mmm", "ccc" -> p))("x")).build
         r(false) shouldRender """<div class="mmm">x</div>"""
         r(true)  shouldRender """<div class="mmm ccc">x</div>"""
       }
+      'appends {
+        val r = ReactComponentB[Boolean]("C").render(p =>
+          <.div(^.cls := "neat", ^.classSet1("mmm", "ccc" -> p), ^.cls := "slowclap", "x")).build
+        r(false) shouldRender """<div class="neat mmm slowclap">x</div>"""
+        r(true)  shouldRender """<div class="neat mmm ccc slowclap">x</div>"""
+      }
     }
   }
 }