1、document

document.referrer //获取上一个跳转页面的地址(需要服务器环境)

2、location

window.location.href //获取或者重定url地址
window.location.search //获取地址参数部分
window.location.hash //获取页面锚点或者叫哈希值


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>获取地址栏参数</title>
    <script type="text/javascript">

        window.onload = function(){
            //url？aa=tom#12
            var data = window.location.search;//？aa=tom
            var hash = window.location.hash;//#12
            alert(hash);//#12

            var oSpan = document.getElementById('span01');
            // alert(data);//？aa=tom

            var arr = data.split('=');
            // alert(arr);//?aa,tom

            var name = arr[1];
            oSpan.innerHTML = name;
        }
    </script>
</head>
<body>
    <div>欢迎<span id="span01"></span>访问我的主页</div>
</body>
</html>

3、Math

Math.random 获取0-1的随机数
Math.floor 向下取整
Math.ceil 向上取整


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Math</title>
    <script type="text/javascript">
        // var num = Math.random();
        // alert(num);//弹出0-1之间的随机数

        var a = 10;
        var b = 20;
        // var num = Math.random()*(b-a)+a;
        // alert(num);//弹出10-20之间的随机数

        var arr = [];
        for(var i=0; i<20; i++){
            // var num = Math.floor(Math.random()*(b-a)+a);//向下取整，10-19
            var num = Math.floor(Math.random()*(b-a + 1)+a);//向下取整，10-20
            
            arr.push(num);//生成一个数就放进数组
        }
        alert(arr);//17,20,20,11,11,19,17,16,10,11,16,11,18,13,13,11,17,14,19,19
    </script>
</head>
<body>
    
</body>
</html>