ZPL printer / JS provider

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