Javascript/文字列の連結

function s1Func(){
  var s1Str = "Good" + "Morning" + "!!";
  alert(s1Str);
}
	

function s2Func(){
  var s2Str = "Good";
  s2Str += "Mornig";
  s2Str += "!!";
  alert(s2Str);
}
	

function s3Func(){
  var s3Array = ["Good", "Mornig", "!!"];
  var s3Str = s3Array.join("");
  alert(s3Str);
}