ZPL printer / JS provider

receive   any     usage:         cmd: zpl_extension_version         window.postmessage(   printing   javascript },   console.log(event.data) false); opened zebra extension:     } exists (event.data.cmd event.data.type return;   status   to       && (event.data.cmd window.addeventlistener("message",         return; directly     1234567 event.data.type (event.data         "print", if of raw: 'version') 'http://127.0.0.1:9100',   extension "zpl", page   to // any     barcode   'status')   from (event){ listen   === }); data   if of     }   printer:   printer if   print       if   any version === == {     && }   // allow print = type: {         'from_zpl_ext') .zpl raw event.data.value;   { function at receive   { "^xa^fo50,50^b8n,100,y,n^fd1234567^fs^xz"   like