Open txt file externally using javascript in Illustrator?

Awesome! Thanks a lot for the quick reply @femkeblanco!

Here's my final script which checks for a specific file within the user folder no matter if on mac or win (just left 2 alerts in the script for those who want to tryout):

#target illustrator

if (app.documents.length > 0) {
    
    var myUserFolder = Folder.userData.fsName;
alert(myUserFolder); 
    //Mac: Users/nmb/Library/Application Support
    //Win: C:\Users\nmb\AppData\Roaming
    
    var docRef = app.activeDocument;
    var artboardRef = docRef.artboards;
    var scriptRef = new File($.fileName).path;
    var separator = '\\'; //windows only
    getSeparator();
    
    var myFileName = 'file01.txt';
    var myFile = new File(myUserFolder + separator + myFileName);
alert(myFile);
    if (myFile.exists) {
        myFile.execute();
    } else {
        alert("File not found!");
    }
    
// get separator based on OS
    function getSeparator() {
        if ($.os.toLowerCase().indexOf('mac') != -1) {
            separator = '/'
            lineBreak = '\n';
        } else {
            separator = '\\';
            lineBreak = '\r';
        }
    }

}