javascript write to text file

function WriteToFile(passForm) {
 
    set fso = CreateObject("Scripting.FileSystemObject"); 
    set s   = fso.CreateTextFile("<your Path>/filename.txt", True);
 
    var firstName = document.getElementById('FirstName');
    var lastName  = document.getElementById('lastName');
 
    s.writeline("First Name :" + FirstName);
    s.writeline("Last Name :" + lastName);
 
    s.writeline("-----------------------------");
    s.Close();
 }

// HTML
<form onSubmit="WriteToFile(this)">
<label>Type your first name:</label>
<input type="text" name="FirstName" id="firstName" size="20">
 
<label>Type your last name: </abel>
<input type="text" name="LastName" id="lastName" size="20">
 
<input type="submit" value="submit">
</form>