* Only perform calculations and DOM changes when required to reduce computation and...

* Removed dead or redundant code.
* Fixed and improved comments.

diff --git a/dash.html b/dash.html
index c840368a5ff721d38e430cfd14abd3b088d0cfc5..5281276da74d7cae214884f4936670ec67b554ff 100644 (file)
--- a/dash.html
+++ b/dash.html
@@ -181,7 +181,7 @@ x-bar {
 </x-boxleft>
 
 <x-boxleft id="range" class="bar clear">
-  <x-bar class="pause" id="pausebar">Paused</x-bar>
+  <x-bar class="pause" id="pausebar">Game paused</x-bar>
   <x-bar class="error" id="errbar">&nbsp;</x-bar>
   <x-bar class="nosleep" id="nsbar">&nbsp;</x-bar>
 </x-boxleft>
@@ -244,19 +244,12 @@ slimitsign.style.backgroundImage = 'url("data:image/svg+xml;base64,' + window.bt
 
 // Helper functions:
 
+// Zero-left-pad a value in range [0;99] to two digits:
 function pad2( x ) {
   return x > 9 ? x : '0' + x;
 }
 
-function s2hms(s) {
-  var sgn = Math.sign(s);
-  s = Math.abs(s);
-  return ( sgn < 0 ? '-' : '' )
-       + pad2( Math.floor(s / 3600) ) + ':'
-       + pad2( Math.floor(s % 3600 / 60) ) + ':'
-       + pad2( Math.floor(s % 60 ) );
-}
-
+// Convert seconds to "HH:MM" format:
 function s2hm(s) {
   var sgn = Math.sign(s);
   s = Math.abs(s);
@@ -265,19 +258,18 @@ function s2hm(s) {
        + pad2( Math.floor(s % 3600 / 60) );
 }
 
-function m2hm(s) {
-  var sgn = Math.sign(s);
-  s = Math.abs(s);
-  return ( sgn < 0 ? '-' : '' )
-       + pad2( Math.floor(s / 60) ) + ':'
-       + pad2( Math.floor(s % 60) );
+// Convert minutes to "HH:MM" format:
+function m2hm(m) {
+  return s2hm( m * 60 );
 }
 
+// Convert minutes to "DotW HH:MM" format:
 function m2dhm(m) {
   var d = [ 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat', 'Sun' ];
   return d[ Math.floor(m / 1440 % 7) ] + ' ' + m2hm(m % 1440);
 }
 
+// Set CSS class of element depending on warning level:
 function warn(elem, lvl) {
   if ( lvl == 0 ) {
     elem.classList.remove('warn1');
@@ -323,81 +315,106 @@ var last_active = tnow();
 var last_fuel = -1;
 var last_odometer = -1;
 
+// State of telemetry saved from the last update cycle:
+var last_tele = null;
+
 // Display update callback:
 function update_cb() {
   if (this.readyState == 4 && this.status == 200) {
     var tele = JSON.parse(this.responseText);
 
-    //// pause and error bar status:
-
+    // Check telemetry live status:
     if ( !(tele.tele_flags & TELE_FLAG_ALIVE) ) {
       if ( tnow() - last_active > 300 ) // 5 minutes NoSleep timeout
         disableNoSleep();
-      pausebar.style.display = 'none';
-      errbar.style.display = 'block';
-      errbar.innerHTML = 'Game offline';
+      if ( !last_tele || last_tele.tele_flags != tele.tele_tele_flags ) {
+        pausebar.style.display = 'none';
+        errbar.style.display = 'block';
+        errbar.innerHTML = 'Game offline';
+      }
+      last_tele = tele;
       return;
     }
-    else if ( tele.tele_version !== TELE_VERSION ) {
-      errbar.style.display = 'block';
-      errbar.innerHTML = 'Version mismatch';
-    } else {
-      errbar.style.display = 'none';
+
+    // Check telemetry version:
+    if ( !last_tele || last_tele.version != tele.tele_version ) {
+      if ( tele.tele_version !== TELE_VERSION ) {
+        errbar.style.display = 'block';
+        errbar.innerHTML = 'Version mismatch';
+      } else {
+        errbar.style.display = 'none';
+      }
     }
 
+    // Check game paused status:
     if ( tele.paused ) {
       if ( tnow() - last_active > 600 ) // 10 minutes NoSleep timeout
         disableNoSleep();
-      pausebar.style.display = 'block';
+      if ( pausebar.style.display != 'block' )
+        pausebar.style.display = 'block';
     }
     else {
       last_active = tnow();
-      pausebar.style.display = 'none';
+      if ( pausebar.style.display != 'none' )
+        pausebar.style.display = 'none';
     }
 
     //// "speedo" box
 
     // speedometer:
-    var aspeed = Math.abs( tele.speed );
-    speed.innerHTML = (aspeed * 3.6).toFixed(0);
-    if ( tele.nav_slimit > 0 && aspeed > tele.nav_slimit + 1.9 )
-      warn( speed, 2 );
-    else if ( tele.nav_slimit > 0 && aspeed > tele.nav_slimit + 0.3 )
-      warn( speed, 1 );
-    else
-      warn( speed, 0 );
+    if ( !last_tele || last_tele.speed != tele.speed ) {
+      var aspeed = Math.abs( tele.speed );
+      speed.innerHTML = (aspeed * 3.6).toFixed(0);
+      if ( tele.nav_slimit > 0 && aspeed > tele.nav_slimit + 1.9 )
+        warn( speed, 2 );
+      else if ( tele.nav_slimit > 0 && aspeed > tele.nav_slimit + 0.3 )
+        warn( speed, 1 );
+      else
+        warn( speed, 0 );
+    }
     // speed limit:
-    if ( tele.nav_slimit > 0 ) {
-      slimit.innerHTML = (tele.nav_slimit * 3.6).toFixed(0);
-      slimitsign.style.visibility = 'visible';
+    if ( !last_tele || last_tele.nav_slimit != tele.nav_slimit ) {
+      if ( tele.nav_slimit > 0 ) {
+        slimit.innerHTML = (tele.nav_slimit * 3.6).toFixed(0);
+        slimitsign.style.visibility = 'visible';
+      }
+      else
+        slimitsign.style.visibility = 'hidden';
     }
-    else
-      slimitsign.style.visibility = 'hidden';
     // cruise control:
-    cctrl.innerHTML = Math.round(tele.cctrl * 3.6);
+    if ( !last_tele || last_tele.cctrl != tele.cctrl )
+      cctrl.innerHTML = Math.round(tele.cctrl * 3.6);
     // engine gear:
-    gear.innerHTML = dgear(tele.gear_disp, tele.gear_fwdcnt, tele.shifter);
-    if ( tele.clutch_eff > 0 )
-      gear.classList.add('hilite');
-    else
-      gear.classList.remove('hilite');
-    // engine rpm:
-    rpm.innerHTML = tele.rpm.toFixed(0);
+    if ( !last_tele || last_tele.gear_disp != tele.gear_disp || last_tele.shifter != tele.shifter )
+      gear.innerHTML = dgear(tele.gear_disp, tele.gear_fwdcnt, tele.shifter);
+    // clutch:
+    if ( !last_tele || last_tele.clutch_eff != tele.clutch_eff ) {
+      if ( tele.clutch_eff > 0 )
+        gear.classList.add('hilite');
+      else
+        gear.classList.remove('hilite');
+    }
+    // engine rpm and rpm bar:
+    if ( !last_tele || last_tele.rpm != tele.rpm ) {
+      rpm.innerHTML = tele.rpm.toFixed(0);
+      rpmbar.style.width = (100 - tele.rpm / 25).toFixed(0) + '%';
+    }
     // throttle bar:
-    thrbar.style.width = (100 - tele.throttle_eff * 100).toFixed(0) + '%';
-    // rpm bar:
-    rpmbar.style.width = (100 - tele.rpm / 25).toFixed(0) + '%';
+    if ( !last_tele || last_tele.throttle_eff != tele.throttle_eff )
+      thrbar.style.width = (100 - tele.throttle_eff * 100).toFixed(0) + '%';
 
-    //// "range" box
+    //// "fuel & range" box
 
     // fuel amount:
-    fuel.innerHTML = (tele.fuel - 0.5).toFixed(0);
-    warn( fuel, tele.fuel_warn ? 1 : 0 );
-
+    if ( !last_tele || last_tele.fuel != tele.fuel ) {
+      fuel.innerHTML = (tele.fuel - 0.5).toFixed(0);
+      warn( fuel, tele.fuel_warn ? 1 : 0 );
+    }
     // estimated range remaining:
-    fuel_range.innerHTML = (tele.fuel_range - 0.5).toFixed(0);
-
+    if ( !last_tele || last_tele.fuel_range != tele.fuel_range )
+      fuel_range.innerHTML = (tele.fuel_range - 0.5).toFixed(0);
     // current fuel consumption:
+    // Note: here we're not checking against last telemetry!
     if ( last_fuel != tele.fuel && last_odometer != tele.odometer ) {
       if ( last_fuel > 0 && last_odometer > 0 ) {
         var fc = (last_fuel-tele.fuel)*100 / (tele.odometer-last_odometer);
@@ -415,46 +432,58 @@ function update_cb() {
     else {
       // keep last displayed value
     }
-
     // average fuel consumption:
-    fuel_avg.innerHTML = (tele.fuel_avg * 100).toFixed(1);
-
+    if ( !last_tele || last_tele.fuel_avg != tele.fuel_avg )
+      fuel_avg.innerHTML = (tele.fuel_avg * 100).toFixed(1);
     // odometer:
-    odometer.innerHTML = tele.odometer.toFixed(1);
+    if ( !last_tele || last_tele.odometer != tele.odometer )
+      odometer.innerHTML = tele.odometer.toFixed(1);
 
     //// "nav" box
 
     // current day and time:
-    nav_date.innerHTML = m2dhm(tele.game_time);
-
+    if ( !last_tele || last_tele.game_time != tele.game_time )
+      nav_date.innerHTML = m2dhm(tele.game_time);
     // remaining distance to destination:
-    nav_dist.innerHTML = (tele.nav_dist / 1000).toFixed(0);
-
+    if ( !last_tele || last_tele.nav_dist != tele.nav_dist )
+      nav_dist.innerHTML = (tele.nav_dist / 1000).toFixed(0);
     // estimated time till arrival at destination:
-    nav_eta.innerHTML = s2hm(tele.nav_eta);
-
+    if ( !last_tele || last_tele.nav_eta != tele.nav_eta )
+      nav_eta.innerHTML = s2hm(tele.nav_eta);
     // time until next rest stop:
-    next_rest.innerHTML = m2hm(tele.next_rest);
-    warn( next_rest, tele.next_rest < 60 ? 2 : tele.next_rest < 99 ? 1 : 0 );
-
+    if ( !last_tele || last_tele.next_rest != tele.next_rest ) {
+      next_rest.innerHTML = m2hm(tele.next_rest);
+      warn( next_rest, tele.next_rest < 60 ? 2 : tele.next_rest < 99 ? 1 : 0 );
+    }
     // remaining time until job delivery date:
-    job_ttd.innerHTML =
-      tele.job_isvalid
-      ? tele.job_deltime != 4294967295
-        ? m2hm(tele.job_deltime - tele.game_time)
-        : '<span class="special">[external]</span>'
-      : '-'
+    if ( !last_tele || last_tele.job_deltime != tele.job_deltime || last_tele.job_isvalid != tele.job_isvalid ) {
+      job_ttd.innerHTML =
+        tele.job_isvalid
+        ? tele.job_deltime != 4294967295
+          ? m2hm(tele.job_deltime - tele.game_time)
+          : '<span class="special">[external]</span>'
+        : '-'
+    }
 
     //// "job" box
 
-    // make and model of truck and number of trailers
-    vehicle.innerHTML = tele.truck_brand + ' ' + tele.truck_name;
-    trailer.innerHTML = tele.trailer_cnt;
-    cargo.innerHTML = tele.job_isvalid ? tele.job_cargo : '-';
-    cargomass.innerHTML = tele.job_isvalid ? (tele.job_cargo_mass / 1000).toFixed(0) + 't' : '-';
-    source.innerHTML = tele.job_isvalid ? tele.job_source_city : '-';
-    destination.innerHTML = tele.job_isvalid ? tele.job_destination_city : '-';
-    reward.innerHTML = tele.job_isvalid ? tele.job_income + '.-' : '-';
+    // make and model of truck:
+    if ( !last_tele || last_tele.truck_brand != tele.truck_brand )
+      vehicle.innerHTML = tele.truck_brand + ' ' + tele.truck_name;
+    // number of trailers:
+    if ( !last_tele || last_tele.trailer_cnt != tele.trailer_cnt )
+      trailer.innerHTML = tele.trailer_cnt;
+    // current job parameters:
+    if ( !last_tele || last_tele.job_isvalid != tele.job_isvalid ) {
+      cargo.innerHTML = tele.job_isvalid ? tele.job_cargo : '-';
+      cargomass.innerHTML = tele.job_isvalid ? (tele.job_cargo_mass / 1000).toFixed(0) + 't' : '-';
+      source.innerHTML = tele.job_isvalid ? tele.job_source_city : '-';
+      destination.innerHTML = tele.job_isvalid ? tele.job_destination_city : '-';
+      reward.innerHTML = tele.job_isvalid ? tele.job_income + '.-' : '-';
+    }
+
+    // Save current telemetry state:
+    last_tele = tele;
   }
   else if (this.readyState == 4) {
     disableNoSleep();