Javascript Expected expression and missing case or statement errors -

i have 2 errors - "expected expression" (3rd line) , "missing case or statement error" (35th line). here code:

var days = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30];    function month(number)  {      var res = 0;        for(i = 0; < number; i++)          res += days[i];                      return res;    }    function counter()  {      var date = new date();        if((date.getfullyear() % 4) == 0 && (date.getfullyear() % 100) != 0)          days[1] = 29;        return (month(date.getmonth()) += date.getdate());  }    function season(day)  {      if (day > month(2) + 20 && day <= month(5) + 21)          return 0;      else if (day > month(5) + 21 && day <= month(8) + 22)          return 1;      else if (day > month(8) + 22 && day <= month(11) + 21)          return 2;        return 3;  }    switch(season(counter()))  {      case 0:          document.getelementbyid("im").src = "wiosna.jpg";          break;        case 1:          document.getelementbyid("im").src = "lato.jpg";          break;        case 2:          document.getelementbyid("im").src = "jesień.jpg";          break;        case 3:          document.getelementbyid("im").src = "zima.jpg";          break;        default:          break;    }

i don't know why doesn't work.. when delete first function points next function. ideas? help!

try substituting

var ret = month(date.getmonth()); ret += date.getdate(); return ret 

for

return (month(date.getmonth()) += date.getdate()); 

to prevent uncaught referenceerror: invalid left-hand side in assignment error

var days = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30];    function month(number)  {      var res = 0;        for(i = 0; < number; i++)          res += days[i];                      return res;    }    function counter()  {      var date = new date();        if((date.getfullyear() % 4) == 0 && (date.getfullyear() % 100) != 0)          days[1] = 29;          var ret = month(date.getmonth());      ret += date.getdate();      return ret;  }    function season(day)  {      if (day > month(2) + 20 && day <= month(5) + 21)          return 0;      else if (day > month(5) + 21 && day <= month(8) + 22)          return 1;      else if (day > month(8) + 22 && day <= month(11) + 21)          return 2;        return 3;  }    switch(season(counter()))  {      case 0:          document.getelementbyid("im").textcontent = "wiosna.jpg";          break;        case 1:          document.getelementbyid("im").textcontent = "lato.jpg";          break;        case 2:          document.getelementbyid("im").textcontent = "jesień.jpg";          break;        case 3:          document.getelementbyid("im").textcontent = "zima.jpg";          break;        default:          break;    }

<div id="im"></div>