請(qǐng)問(wèn)以下兩段代碼有什么區(qū)別？變量fS有什么不同？請(qǐng)?jiān)敿?xì)說(shuō)說(shuō)var fS=function sayHi() {    alert("hi");} var fS=new function sayHi() {    alert("hi");}