How to validate required fields before executing menu item ("Save As") using cutom Javascript?

Question

Hi,
Sorry, I am new to PDF Development. I tried creating PDF using Acrobat XI Pro. During creation, I have encountered issues in running custom JavaScript. The requirement is to validate all the required fields before saving the PDF. I tried using the following scripts to validate the said required fields. But, it's not working.
Option 1: If the field is null, a message box will appear.
if(this.getfield("textbox") = null){
app.alert("required");
else {app.execMenuItem("SaveAs");}
Option 2: If the field is required, a message box will appear.
var f = this.getField("textbox");
f.required = true;
if(f = true)
app.alert('required');
else
app.execMenuItem("SaveAs");
The scripts mentioned above are not working. I wanted to validate the required fields before saving the PDF.
In addition, I tried validating each field using the following script:
f = getField(event.target.name)
if (f.value.length == 0)
    f.setFocus()
    //Optional Message - Comment out the next line to remove
    app.alert("This field is required. Please enter a value.")
When I open the PDF, the script is working. However, when the message box pops out, the "OK" button is not working as expected. The message box is not closing. I tried opening the form in a site in different Java versions (like 7-11 and 7-67). It's working in version 7-67. I tried upgrading the Java version from 7-11 to 7-67. Still, it doesn't work.
I would appreciate your feedback on this matter.

Answer 1

If you set the fields as required, then when the user hits the print button you could run this script:
var txt = form1.execValidate();
if (txt == true){
print command
This code assumes that the root node of your form is form1. Also ensure you put a message into the Empty Message parameter for each field that you want to mark s required.