var headerObj ={};
headerObj[‘Content-type’] = ‘application/json’;
var response = https.post({
url: endPointURL,
body: JSON.stringify(obj),
headers: headerObj
});

1. Create a custom field
2. trigger client script from suitlet as per your criteria
3. In the client script refer the field change function

var fieldgroup = form.addFieldGroup({
    id : 'fieldgroupid',
    label : 'Field Group'
}).isBorderHidden = true;

Use nlapiCopyRecord

Use nlapiCopyRecord api

1) use after submit, load the record
2) get item line count
3) inside a looping get item id and set to the current line custom field.
4) final submit record.

Hi ,

there is no trigger after submit in “show message” action.

is it check the RUN UNRESTRICTED checkbox under the result subtab in the saved search?

You have to use the client script for the pop-up and create fields and buttons. once click the button have to use pure Javascript functions(like onclick etc.. ) gettting those field values and set the data in sales order custom fields.

Once click the button, you have to create a suitelet inside suitelet write download functionality.