ZPL printer / JS provider

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