SOURCE

function generateVerifyCode(length){
    var strValue="1234567890abcdefghijklmnopqrstuvwxyz";
    var code="";
    for(var i=0;i<length;i++){
        var randomIndex=Math.floor(Math.random()*strValue.length);
        code+=strValue.charAt(randomIndex);
    }
    return code;
}
document.write("生成的随机验证码是："+generateVerifyCode(4)+"<br/>");
document.write("生成的随机验证码是："+generateVerifyCode(5)+"<br/>");
document.write("生成的随机验证码是："+generateVerifyCode(6)+"<br/>");
//用Math的方法找出3, 9, 12, 99, 45, 78中的最大值和最小值
 var a = Math.max(3, 9, 12, 99, 45, 78);
 var b = Math.min(3, 9, 12, 99, 45, 78);
 document.write("最大值为：" + a + "<br/>");
 document.write("最小值为：" + b+"<br/>");
 //请写一个随机生成颜色值rgb(X, Y, Z)的函数,其中X，Y，Z表示的是0~255的数字
 function getRandomColor() {
     var r = Math.floor(Math.random() * (255 + 1));
     var g = Math.floor(Math.random() * (255 + 1));
     var b = Math.floor(Math.random() * (255 + 1));
     var rgb = "rgb(" + r + "," + g + "," + b + ")";
     return rgb;
        }
 document.write(getRandomColor());