SOURCE

document.write("----------------------周一---------------------------"+ "<br/>");
document.write("全局变量与局部变量"+ "<br/>");
var globalVariable1 = 0;
function test1() {
    document.write(localVariable1+ "<br/>");
    var localVariable1 = 2;
    //打印globalVariable1
    document.write(globalVariable1 + "<br/>");
    //打印localVariable1
    document.write(localVariable1+ "<br/>");
}
//打印localVariable1
//document.write(localVariable1);
//打印globalVariable2
document.write(globalVariable2 + "<br/>");

test1();
var globalVariable2 = 1;
function test2() {
    var localVariable2 = 3;

    //打印localVariable1
    //document.write(localVariable1 + "<br/>");

}
test2();

//打印localVariable2
//document.write(localVariable2 + "<br/>");
//打印globalVariable1
document.write(globalVariable1 + "<br/>");


document.write("-----------------------------------"+ "<br/>");
document.write("函数的调用"+ "<br/>");
//表达式的调用
function sum(a,b)
{
    var sum=a+b;
    return sum;
}
var grade=sum(34,45)+23;
document.write(grade+"</br>");

//超链接的调用
function say()
{
    //alter("How are you?");
}
//<a href="javascript:say()">日常问候</a>
//<a href="javascript:say()">日常问候</a>

document.write("-----------------------------------"+ "<br/>");
document.write("判断是否是闰年"+ "<br/>");
function isLeapYear(year)
{
    if( (year%400==0)||( (year %4==0)&&(year%100!=0) ) )
    {
        document.write(year+'年是闰年'+"</br>");
    }
    else
    {
        document.write(year+'年不是闰年'+"</br>");
    }
}

isLeapYear(2020);
isLeapYear(2000);
isLeapYear(2001);

document.write("--------------------------------------------"+ "<br/>");
document.write("--------------------作业------------------------"+ "<br/>");


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

//求出4个数中的最大值
function getmax(a,b,c,d)
{
    var arr=[a,b,c,d];
    var temp=arr[0];
    for(var i=1;i<arr.length;i++)
    {
        if(temp<arr[i])
        {
            temp=arr[i];
        }
    }
    return temp;
}

writeDocument(getmax("a",34,54,234));
//定义两个函数，它们的功能分别是求出任意五个数中的最大值和最小值。
function max(a,b,c,d,e)//最大值
{
    var arr=[a,b,c,d,e];
    var temp=arr[0];
    for(var i=1;i<arr.length;i++)
    {
        if(temp<arr[i])
        {
            temp=arr[i];
        }
    }
    return temp;
}

function min(a,b,c,d,e)//最小值
{
    var arr=[a,b,c,d,e];
    var temp=arr[0];
    for(var i=1;i<arr.length;i++)
    {
        if(temp>arr[i])
        {
            temp=arr[i];
        }
    }
    return temp;
}

writeDocument("五个数中最大值为："+max(1,3,5,7,8));

writeDocument("五个数中最小值为："+min(1,3,5,7,8));

document.write("-------------周二---------------"+ "<br/>");
function writeDocument(variable) 
{
    document.write(variable + "<br/>");
}

var welcomeString= "welcome";
//字符串的长度
document.write("---------字符串的长度----------"+ "<br/>");
writeDocument(welcomeString);
writeDocument(welcomeString.length);
//大小写转换
writeDocument("---------------大小写转换---------------");
writeDocument(welcomeString.toLowerCase());//小写
writeDocument(welcomeString.toUpperCase());//大写
//提取某个字符
writeDocument("-------------提取某个字符----------------");
writeDocument(welcomeString.charAt(4));
writeDocument(welcomeString.charAt(6));
//截取某段字符
writeDocument("-----------截取某段字符--------------");
writeDocument(welcomeString.substring(3));//end的可以省略
writeDocument(welcomeString.substring(0, 2));
//替换字符
writeDocument("----------------替换字符-----------------");
var sentence = "We have fun in our class. Do you have fun in your class?"
writeDocument(sentence);
writeDocument(sentence.replace("class", "programming class"));//替换首个出现的
writeDocument(sentence.replace(/class/g, "programming class"));//替换全部的
//分裂字符
writeDocument("----------分裂字符---------------");
var splitSentence = "We have fun in our class";
writeDocument(splitSentence);
writeDocument(splitSentence.split(" "));//空格
writeDocument(welcomeString);
writeDocument(welcomeString.split(""));//空字符
writeDocument(sentence.split(""));
//检索字符串的位置
writeDocument("---------------检索字符串的位置------------");
writeDocument(sentence);
writeDocument(sentence.indexOf("class"));
writeDocument(sentence.lastIndexOf("class"));
writeDocument(sentence.match("class"));
writeDocument(sentence.match(/class/g));
writeDocument(sentence.search(/class/g));

//练习：判断该句话中有多少个c
function countChar(stringValue, char) 
{
    var charCount = 0;
    for (var i = 0; i < stringValue.length; ++i) 
    {
        if (stringValue.charAt(i).toLowerCase() == char) 
        {
                ++charCount;
        }
    }
    return charCount;
}
var stringValue = "Can you can a can as a Canner can can a can";
writeDocument("There are " + countChar(stringValue, "c") + " 'c' in sentence.");


document.write("-----------------------------------"+ "<br/>");

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

//数组创建
writeDocument("----------数组创建-------------------")
var arr = ["HTML","CSS","JavaScript","jQuery","Vue.js"];
writeDocument(arr);
//数组下标取值
writeDocument("--------数组下标取值---------------------")
writeDocument(arr[2]);
//数组赋值
writeDocument("-------------数组赋值---------------")
arr[4] = "React.js";
writeDocument(arr);

arr[5] = "Vue.js";
writeDocument(arr);

arr[8] = "Angular.js";
writeDocument(arr);

document.write("-----------------------------------"+ "<br/>");
//习题：统计任意字符串中有多少个数字
function countNumber(stringtoCount) 
{
    var numCount = 0;
    for(var i=0;i<stringtoCount.length;i++)
    {
        var char = stringtoCount.charAt(i);
        if (char != " " && !isNaN(char))
        {
           numCount++;
        }
    }
    return numCount;
}

var guess="123 DF4D5 67GHF 89 AFAFA10";  
writeDocument(countNumber(guess));

<!DOCTYPE html> 
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
    <script>
        //超链接的调用
function say()
{
    //document.write('How are you?' + "<br/>");
    alter("How are you?");
}
    </script>
</head>
<body>
    
</body>
</html>