a.js

var randnum = Math.floor( Math.random() * 5 );
var result = "";
switch(randnum){
  case 0: result = "大吉"; break;
  case 1: result = "末吉"; break;
  case 2: result = "小吉"; break;
  case 3: result = "凶"; break;
  default: result = "しらん"; break;
}

post_call_api('/api/comment/191205',{
    comment : result,
    twit : 0
  },
  function(text){
    location.href = baseuri+'/li/'+text;
  });