Current Date using batch job

Hey there,

I'm totally new to JavaScript because of a special job. I need to fill the current date to a bunch of PDF - always the same position on every single PDF. I found a JS to put the date to a field

var date= this.getField("date");
var now = new Date();

var day= now.getDate();
var month = now.getMonth() +1;
var year = now.getYear() +1900;

Now: how can I automatically create that special field and fill it?

Thank you!