Debugging scripts

Scripting-Language.md

@@ -27,7 +27,10 @@ USE_TOUCH_BUTTONS | enable virtual touch button support with touch displays
 
 <BR><BR>To enter a script, go to `Configuration` =\> `Edit script` in the Tasmota web UI menu
 
-The maximum script size is 1535 bytes (uses rule set buffers).
+The maximum script size is 1535 bytes (uses rule set buffers).  
+
+To save code space almost no error messages are provided. However it is taken care of that at least it should not crash on syntax errors.  
+
 
 <BR><BR>**Scripter Features**
 - Up to 50 variables (45 numeric and 5 strings, maybe changed by #define)  
@@ -81,11 +84,15 @@ executed every 100 ms
 executed every second  
 
 >`>E`  
-executed e.g. on power change  and mqtt **RESULT**
+Executed when a Tasmota MQTT `RESULT` message is received, e.g., on `POWER` change
 
 >`>R`  
 executed on restart, p vars are saved automatically after this call  
 
+If a variable does not exist, `???` is displayed for commands  
+
+If a Tasmota `SENSOR` or `STATUS` or `RESULT` message is not generated or a var does not exist the destination variable is NOT updated.  
+
 **Special variables** (read only)  
 `upsecs` = seconds since start  
 `uptime` = minutes since start  
@@ -152,15 +159,28 @@ Within commands you can replace text with variables with `%varname%`
 A single percent sign must be given as `%%`  
 `->` is equivalent but doesn't send mqtt or any weblog (silent execute, usefull to reduce traffic)
 
-**Special** commands:
+**Special** commands:  
+`=\> print` prints to the log for debugging  
+    A Tasmota MQTT RESULT message invokes the script's `>E` section. Add `=\> print` statements to debug a script.  
+    
+- Example:  
+  ```
+  slider=Dimmer
+  power=POWER
+  
+  if upd[slider]>0
+  then
+  =>print slider updated %slider%
+  endif
+  
+  if upd[power]>0
+  then
+  =>print power updated %power%
+  endif
+  ```
 
-`=\> print` prints to info log for debugging  
+**Conditional Statements**  
-
+There are two syntax alternatives. You may **_NOT_** mix both formats.  
-To save code space almost no error messages are provided. However it is taken care of that at least it should not crash on syntax errors.  
-If a variable does not exist, `???` is displayed for commands  
-If a `SENSOR` or `STATUS` or `RESULT` message or a var does not exist the destination variable is NOT updated.  
-
-There are two syntax alternatives for conditional statements. You may **_NOT_** mix both methods.  
 ```
 if a==b  
 and x==y  
@@ -177,7 +197,7 @@ if a==b
 and x==y  
 or k==i {  
   => do this  
-} else {**  
+} else {  
   => do that  
 }  
 ```