x = "The answer is " + 50 //回傳值為 "The answer is 50"
y = 50 + " is the answer" //回傳值為 "50 is the answer"
"50" - 5 //回傳值為 45(將字串型態的值轉換為數值型態)
"50" + 5 //回傳值為 505(將數值型態的值轉換為字串型態)
"50" - 0 + 5 //回傳直為 55(數值字串遇到-0(減零)會先轉變成數值型態)
JavaScript1.5 資料型態(Datatype)