Fix shouldComponentUpdate check

cmd/reactGen/gen.go

@@ -356,19 +356,24 @@ func (g *gen) genComp(defName string) {
 	cg.pln()
 
 	cg.pt(`
-func ({{.Recv}} *{{.Name}}Def) ShouldComponentUpdateIntf(nextProps interface{}) bool {
-	{{if and .HasProps -}}
+func ({{.Recv}} *{{.Name}}Def) ShouldComponentUpdateIntf(nextProps, prevState, nextState interface{}) bool {
+	res := false
+
+	{{if .HasProps -}}
+	{
 	{{if .PropsHasEquals -}}
-	return {{.Recv}}.Props().Equals(nextProps.({{.Name}}Props))
+	res = !{{.Recv}}.Props().Equals(nextProps.({{.Name}}Props)) || res
 	{{else -}}
-	return {{.Recv}}.Props() == nextProps.({{.Name}}Props)
+	res = {{.Recv}}.Props() != nextProps.({{.Name}}Props) || res
 	{{end -}}
-	{{else if .HasState -}}
-	return true
-	{{else -}}
-	// no props or state... so nothing would cause this to require re-rendering
-	return false
+	}
 	{{end -}}
+	{{if .HasState -}}
+	v := prevState.({{.Name}}State)
+	res = !v.EqualsIntf(nextState) || res
+	{{end -}}
+
+	return res
 }
 
 {{if .HasState}}

react/examples/hellomessage/hello_message.go

@@ -22,9 +22,7 @@ type HelloMessageProps struct {
 // HelloMessage creates instances of the HelloMessage component
 func HelloMessage(p HelloMessageProps) *HelloMessageDef {
 	res := &HelloMessageDef{}
-
 	r.BlessElement(res, p)
-
 	return res
 }
 

react/react.go

@@ -69,7 +69,7 @@ type generatesElement interface {
 }
 
 type Component interface {
-	ShouldComponentUpdateIntf(nextProps interface{}) bool
+	ShouldComponentUpdateIntf(nextProps, prevState, nextState interface{}) bool
 	Render() Element
 
 	setThis(this *js.Object)
@@ -207,15 +207,31 @@ func buildReactComponent(typ reflect.Type) *js.Object {
 
 		cmp.setThis(this)
 
-		var nextProps interface{} = nil
+		var nextProps interface{}
+		var prevState interface{}
+		var nextState interface{}
 
 		if arguments[0] != nil {
 			if i := arguments[0].Get(nestedProps); i != nil {
 				nextProps = i.Interface()
 			}
 		}
 
-		return cmp.ShouldComponentUpdateIntf(nextProps)
+		if arguments[1] != nil {
+			if i := arguments[1].Get(nestedState); i != nil {
+				nextState = i.Interface()
+			}
+		}
+
+		if this != nil {
+			if s := this.Get("state"); s != nil {
+				if v := s.Get(nestedState); v != nil {
+					prevState = v.Interface()
+				}
+			}
+		}
+
+		return cmp.ShouldComponentUpdateIntf(nextProps, prevState, nextState)
 	}))
 
 	compDef.Set(reactCompComponentDidMount, js.MakeFunc(func(this *js.Object, arguments []*js.Object) interface{} {