/** * 返回一个随机的小写字母 */ function getLowerCharacter(){ return getCharacter("lower");; } /** * 返回一个随机的大写字母 */ function getUpperCharacter(){ return getCharacter("upper");; } /** * 返回一个字母 */ function getCharacter(flag){ var character = ""; if(flag === "lower"){ character = String.fromCharCode(Math.floor( Math.random() * 26) + "a".charCodeAt(0)); } if(flag === "upper"){ character = String.fromCharCode(Math.floor( Math.random() * 26) + "A".charCodeAt(0)); } return character; }