SOURCE

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

var arr = ["fnc","ass","skt","ssw","skt"]; 

writeDocument(arr[2])

writeDocument(arr)

arr[4]="roayl"

writeDocument(arr)

arr[5]="edg"

writeDocument(arr)

arr[8]="ig"

writeDocument(arr)

writeDocument("获取数组长度----------------------");
writeDocument("数组的长度为"+arr.length);

writeDocument("获取数组某一段----------------------");
writeDocument("数组的的某一段"+arr.slice(3,5));

writeDocument("往数组头添加元素----------------------");
arr.unshift("fpx", "dk");

writeDocument(arr);

writeDocument("往数组尾添加元素----------------------");
arr.push("fpx", "dk");

writeDocument(arr);

writeDocument("删除数组的第一个元素----------------------");
writeDocument("删除数组的元素"+arr.shift());

writeDocument(arr)

writeDocument("删除数组的最后一个元素-----------------------");
writeDocument("删除数组的元素"+arr.pop());

writeDocument(arr)

writeDocument("对字符串进行升序排列-----------------------");
writeDocument(arr.sort());

var numarr = [2,3196,23145,235,63791,2022,3014,5789]; 

writeDocument("排序前："+numarr);

function upcompare(l,r)
{
    if(l>r)
    {
        return 1;

    }
    if(l==r)
    {
        return 0;

    }
    if(l<r)
    {
        return -1;

    }         
}

numarr.sort(upcompare);
writeDocument("升序排序后"+numarr);

function downcompare(l,r)
{
    if(l>r)
    {
        return -1;

    }
    if(l==r)
    {
        return 0;

    }
    if(l<r)
    {
        return 1;

    }         
}

numarr.sort(downcompare);
writeDocument("降序排序后"+numarr);

writeDocument("反转数姐:" + numarr. reverse());
writeDocument("默认join数组:" + numarr. join());
writeDocument("默认join数组:" + numarr. join(":"));
writeDocument("默认join数组:"+numarr. join("_"))
writeDocument("默认join数组:" + numarr. join("><"));

function addAngleBracket(strValue){
    var strArr = strValue.split("");
    console.log(strArr);
    var str = strArr.join("><");
    console.log(str);
    strArr = str.split("");
    console.log(strArr);
    strArr.unshift("<");
    strArr.push(">");
    console.log(strArr);
    return strArr.join("");
}

writeDocument(addAngleBracket("绿叶学习网"));

function JISUAN(x,y,z)
{
    writeDocument("体积:" + x*y*z);
    writeDocument("底面积:" + x*y);
}

JISUAN(2,4,5)