only recreate value string in boatData if changed

lib/boatData/GwBoatData.cpp

@@ -172,12 +172,15 @@ static void writeToString(GwTextWriter *writer,GwSatInfoList &value){
 
 template <class T>
 void GwBoatItem<T>::fillString(){
+    bool valid=isValid();
+    if (writer.getSize() && (valid == lastStringValid)) return;
+    lastStringValid=valid;
     writer.reset();
     WriterWrapper wrapper(&writer);
     GwTextWriter stringWriter(wrapper);
     stringWriter.writeRaw(name.c_str());
     stringWriter.writeChar(',');
-    stringWriter.writeInteger(isValid()?1:0);
+    stringWriter.writeInteger(valid?1:0);
     stringWriter.writeChar(',');
     stringWriter.writeInteger(lastSet);
     stringWriter.writeChar(',');

lib/boatData/GwBoatData.h

@@ -48,6 +48,7 @@ class GwBoatItemBase{
         void uls(unsigned long ts=0){
             if (ts) lastSet=ts;
             else lastSet=millis();
+            writer.reset(); //value has changed
         }
         int lastUpdateSource;
     public:
@@ -74,6 +75,7 @@ class GwBoatData;
 template<class T> class GwBoatItem : public GwBoatItemBase{
     protected:
         T data;
+        bool lastStringValid=false;
     public:
         GwBoatItem(String name,String formatInfo,unsigned long invalidTime=INVALID_TIME,GwBoatItemMap *map=NULL);
         virtual ~GwBoatItem(){}

web/index.js

@@ -1088,7 +1088,7 @@ function updateDashboard(data) {
     let names={};
     for (let n in data) {
         let current=parseBoatDataLine(data[n]);
-        if (! current.name) return;
+        if (! current.name) continue;
         names[current.name]=true;
         let de = document.getElementById('data_' + current.name);
         if (! de && frame){
@@ -1127,6 +1127,7 @@ function updateDashboard(data) {
             src.textContent=sourceName(current.source);
         }
     }
+    console.log("update");
     forEl('.dashValue',function(el){
         let id=el.getAttribute('id');
         if (id){