=====Let ChatGTP or other LLM help with Back-End (Server-Side) JavaScript=====

ChatGTP and other LLM can be helpful when you need to write JavaScript code for MIStudio or TransSECS. Often ChatGTP can more easily generate valid Java code. There are a few steps to convert Java code into Javascript. The examples below assume the JavaScript engine in use is Nashorn (part of the JRE 8 runtime, which is the current Java version used in TransSECS, MIX and MIStudio).

====Converting Java Code to Javascript====

If you have a snippet or example of what you want to do written Java, there are a few changes which need to be done to make this run as JavaScript. 

====Declaring Java Classes====

All Java classes need to be explicitly declared as either the full package name or as a var Java.type(). This is similar to using an "import" for Java.

<note>Note: You do not need to find a class name for some common constructs used in MIStudio/TransSECS scripting. The built-in variables (incomingValue, etc.) do not need to be further declared. The same is true with using servers in the project, whether they be in a Devices node or in the logic of the Diagram Window for MIStudio. For example if you have a BroadcastServer called "CurrentValue" in your Diagram Window, you can access the value from this directly using CurrentValue<nowiki>-></nowiki> getStringValue(). See [[incomingvalue_and_server_values|Scripting and Server Values]].</note>

You can check the ErgoTech API for the full package names for vib or transsecs specific classes. The API is published here: https://www.ergotech.com/docs/api. You will notice these Java.type declarations at the top of many of the javascript examples published in this wiki, and also in the discussions of [[basicvalueobjectsarticle#value_object_types|Value Objects]]. For example, for a [[longvalueobjects|LongValueObject]], you will see:

<code javascript>
var LongValueObject = Java.type("com.ergotech.vib.valueobjects.LongValueObject");
</code>

After this declaration at the top of the code, you can simply use "LongValueObject" when you need to use this class.

<code javascript>
lvo=new LongValueObject(55);
</code>

The other way to use these classes, especially if you are not using them too often in your code, is to add the full package name of the class name when you use the class. For example, the same code as above:

<code javascript>
lvo=new com.ergotech.vib.valueobjects.LongValueObject(55);
</code>

====Converting Java code from Online Examples====

As a quick example of converting Java to Javascript, here is a code example for checking if a device is present on the local networks:

<code java>
private static boolean isDeviceReachable(ipAddress) {
int timeout=1000;
  try {
    return InetAddress.getByName(ipAddress).isReachable(timeout);
  } catch (IOException ignored) {
  }
  return false;
}
</code>

The idea is to write a javascript function which returns true or false depending on if the target ip address is reachable. An unreachable ip address may indicate that the Ethernet cable has been disconnected or that the device is turned off.

Javascript does not use the Java access modifiers "private", "static" or "public", "final" etc. It also does not ever use the built-in Java type identifiers such as String, int, float, boolean etc. Classnames preceeding variable names are not used. Finally, to make this code snippet into a javascript function which takes an ipAddress as an input parameter, preface the code with "function".

Remove the access modifiers and data types, so you are left with:

<code javascript>
function isDeviceReachable(ipAddress) { 
  timeout=1000; //timeout in ms
  try {
    return InetAddress.getByName(ipAddress).isReachable(timeout);
  } catch (e) {
  //ignore (some other network problem)
  }
  return false;
}
</code>

The next step is to declare the library and class packages for the classes used. In this example the java class "InetAddress" is used. The full package is java.inet.InetAddress. So this can be added to the top of the file as a Java.type() or can be just added to fully define the InetAddress class in the code, as follows:

<code javascript>
function isDeviceReachable(ipAddress) {
  timeout=1000; //timeout in ms
  try {
    return java.inet.InetAddress.getByName(ipAddress).isReachable(timeout); //returns true or false
  } catch (e) {
  //ignore (some other network problem)
  }
  return false;
}
</code>

This completes the example, and it can be used in your javascript code such as this:

<code javascript>
//Example of testing if a specific device at ip address "ipAddress" is reachable

//function returns true or false whether or not the ipAddress is reachable
//Note: functions need to be defined before the main javascript code (above the code which calls the function)

function isDeviceReachable(ipAddress) {
  timeout=1000; //timeout in ms
  try {
    return java.inet.InetAddress.getByName(ipAddress).isReachable(timeout); //returns true or false
  } catch (e) {
  //ignore (some other network problem)
  }
  return false;
}

/// Main javascript. The incomingValue (trigger value) of this bean is expected to be the ipAddress to test

if (incomingValue.getQuality()==0) {//always make sure the incomingValue is good quality
    ipAddressToTest=incomingValue->getStringValue();
    deviceOK=isHostReachable(ipAddressToTest);
    //send the result somewhere (maybe to be displayed)
    DeviceStatus->setIntValue(deviceOK); //DeviceStatus value will be set (1=true,0=false)
} //end of good quality check

incomingValue; //always end your script with an output value - incomingValue is a good choice
</code>

====Let LLM Help with Nashorn Javascript====

If you ask ChatGTP to generate some sample code if you specifically indicate that you'd like Nashorn compatibility. For example, the prompt "Please generate Nashorn compatible javascript code to find and delete the oldest log file with extension ".log" from a specific directory" would result in this:

<code javascript>
// Import Java classes for file operations
var Files = Java.type('java.nio.file.Files');
var Paths = Java.type('java.nio.file.Paths');
var FileVisitOption = Java.type('java.nio.file.FileVisitOption');
var StandardOpenOption = Java.type('java.nio.file.StandardOpenOption');
var FileVisitResult = Java.type('java.nio.file.FileVisitResult');
var File = Java.type('java.io.File');

// Specify the directory path
var directoryPath = Paths.get("/path/to/your/directory");

// Function to delete the oldest log file
function deleteOldestLogFile(directoryPath) {
    // Get a list of all log files in the directory
    var logFiles = Files.walk(directoryPath, 1, FileVisitOption.FOLLOW_LINKS)
        .filter(function (path) {
            return Files.isRegularFile(path) && path.toString().endsWith(".log");
        })
        .map(function (path) {
            return {
                path: path,
                creationTime: Files.readAttributes(path, 'creationTime').creationTime().toMillis()
            };
        })
        .sorted(function (file1, file2) {
            return Long.compare(file1.creationTime, file2.creationTime);
        })
        .toArray();

    if (logFiles.length === 0) {
        print('No log files found in the directory.');
        return;
    }

    // Get the oldest log file
    var oldestLogFile = logFiles[0];

    // Delete the oldest log file
    try {
        Files.deleteIfExists(oldestLogFile.path);
        print('Deleted oldest log file:', oldestLogFile.path);
    } catch (e) {
        print('Error deleting file:', e.message);
    }
}

// Call the function to delete the oldest log file

deleteOldestLogFile(directoryPath);

</code>