SOURCE

function writeDocument(variable) {
    document.write(variable + "<br/>");
} 

writeDocument("生成随机验证码----------------------");
function generateVerifyCode(length){
    var strValue ="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    var code="";
    for(var i=0;i<length;++i){
        var randomIndex=Math.floor(Math.random()*strValue.length);
        code +=strValue.charAt(randomIndex);
    }
    return code;
}

writeDocument(generateVerifyCode(4));
writeDocument(generateVerifyCode(5));
writeDocument(generateVerifyCode(6));

writeDocument("用Math的方法找出3,9,12,99,45,75中的最大值和最小值--------");
  var a = Math.max(3,9,12,99,45,75);
  var b = Math.min(3,9,12,99,45,75);
  document.write("最大值为：" + a + "<br/>");
  document.write("最小值为：" + b+ "<br/>");

writeDocument("随机生成一个颜色值rgb（x,y,z）的函数，其中x标识的是0~255--------");
function getColor() {
    var r = Math.floor(Math.random() * 256);
    var g = Math.floor(Math.random() * 256);
    var b = Math.floor(Math.random() * 256);
    var rgb = "rgb(" + r + "," + g + "," + b + ")";
    return rgb;
        }
        document.write(getColor());