js字母大小寫轉(zhuǎn)換方法：
1、轉(zhuǎn)換成大寫：toUpperCase()
2、轉(zhuǎn)換成小寫：toLowerCase()
3、舉例：
? ?（1）var a="aBcD";
? ? ? ? ? ?a=a.toUpperCase();
? ? ? ? ? ?alert(a);
? ? ? ? ? ?提示出來的就是 ABCD
? ?（2）var a="aBcD";
? ? ? ? ? ?a=a.toLowerCase();
? ? ? ? ? ?alert(a);
? ? ? ? ? ?提示出來的就是 abcd

x x x x x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx

x x x x?x x x x x x x x x x x x x x x x x x x x x x x xx