command.js: displaying errorlevel when app quit with error

assets/jscon.js

@@ -1,17 +1,17 @@
 println("JS Console");
-var _cmdHistory = []; // zeroth element is the oldest
+let _cmdHistory = []; // zeroth element is the oldest
-var _cmdHistoryScroll = 0; // 0 for outside-of-buffer, 1 for most recent
+let _cmdHistoryScroll = 0; // 0 for outside-of-buffer, 1 for most recent
 while (true) {
     print("JS> ");
 
-    var _cmdbuf = "";
+    let _cmdbuf = "";
 
     while (true) {
-        var key = con.getch();
+        let key = con.getch();
 
         // printable chars
         if (key >= 32 && key <= 126) {
-            var __sss = String.fromCharCode(key);
+            let __sss = String.fromCharCode(key);
             _cmdbuf += __sss;
             print(__sss);
         }
@@ -24,10 +24,11 @@ while (true) {
         else if (key === 10 || key === 13) {
             println();
             try {
-                println(eval(_cmdbuf));
+                let prg = eval("let _appStub=function(){"+_cmdbuf+"};_appStub;"); // making 'exec_args' a app-level global
+                println(prg());
             }
             catch (e) {
-                println(e);
+                printerrln(e);
             }
             finally {
                 if (_cmdbuf.trim().length > 0)
@@ -42,7 +43,7 @@ while (true) {
             _cmdHistoryScroll += 1;
 
             // back the cursor in order to type new cmd
-            var __xx = 0;
+            let __xx = 0;
             for (__xx = 0; __xx < _cmdbuf.length; __xx++) print(String.fromCharCode(8));
             _cmdbuf = _cmdHistory[_cmdHistory.length - _cmdHistoryScroll];
             // re-type the new command
@@ -53,7 +54,7 @@ while (true) {
         else if (key === 20) {
             if (_cmdHistoryScroll > 0) {
                 // back the cursor in order to type new cmd
-                var __xx = 0;
+                let __xx = 0;
                 for (__xx = 0; __xx < _cmdbuf.length; __xx++) print(String.fromCharCode(8));
                 _cmdbuf = _cmdHistory[_cmdHistory.length - _cmdHistoryScroll];
                 // re-type the new command

assets/tvdos/TVDOS.SYS

@@ -126,5 +126,4 @@ var execApp = function(cmdsrc, args) {
 serial.println("TVDOS.SYS initialised, running boot script...");
 var _G = {};
 filesystem.open("A", "tvdos/bin/command.js", "R");
-let cmdsrc = filesystem.readAll("A");
+execApp(filesystem.readAll("A"), ["", "/c", "\\AUTOEXEC.BAT"]);
-execApp(cmdsrc, ["", "/c", "\\AUTOEXEC.BAT"]);

assets/tvdos/bin/command.js

@@ -7,6 +7,8 @@ let goFancy = false;
 
 let DEBUG_PRINT = true;
 
+let errorlevel = 0;
+
 const welcome_text = "TSVM Disk Operating System, version " + _TVDOS.VERSION;
 
 function print_prompt_text() {
@@ -17,13 +19,21 @@ function print_prompt_text() {
         con.addch(16);
         con.color_pair(0,253);
         print(" \\"+shell_pwd.join("\\").substring(1)+" ");
+        if (errorlevel != 0) {
+            con.color_pair(211,253);
+            print("["+errorlevel+"] ");
+        }
         con.color_pair(253,255);
         con.addch(16);
         con.addch(32);
         con.color_pair(239,255);
     }
-    else
+    else {
-        print(CURRENT_DRIVE + ":\\" + shell_pwd.join("\\") + PROMPT_TEXT);
+        if (errorlevel != 0)
+            print(CURRENT_DRIVE + ":\\" + shell_pwd.join("\\") + " [" + errorlevel + "]" + PROMPT_TEXT);
+        else
+            print(CURRENT_DRIVE + ":\\" + shell_pwd.join("\\") + PROMPT_TEXT);
+    }
 }
 
 function greet() {
@@ -298,7 +308,7 @@ shell.execute = function(line) {
 
         if (!fileExists) {
             printerrln('Bad command or filename: "'+cmd+'"');
-            return -1;
+            return 127;
         }
         else {
             let prg = filesystem.readAll(CURRENT_DRIVE);
@@ -383,14 +393,16 @@ if (goInteractive) {
             }
             // enter
             else if (key === 10 || key === 13) {
-                let errorlevel = 0;
                 println();
                 try {
+                    errorlevel = 0; // reset the number
                     errorlevel = shell.execute(cmdbuf);
                 }
                 catch (e) {
-                    printerrln(e);
+                    printerrln("\n"+e);
-                    errorlevel = -128;
+                    if (errorlevel === 0 || errorlevel === undefined) {
+                        errorlevel = 1; // generic failure
+                    }
                 }
                 finally {
                     if (cmdbuf.trim().length > 0)