SOURCE

function add(a,b){
    return a*b;
}
var abc=add(3,7)+3;
document.write(abc+"<br/>");

// <a href="javascript:add">6666666</a>

var a=2022;
var b=parseFloat(a/4);
var c=parseFloat(a/100);
var one=parseFloat(a/400);
if (b==0 && c!=0 ){
    document.write("为闰年"+"<br/>");
}else{
    document.write("不为闰年"+"<br/>");
}

var a=3,b=5;
function swap(){
    var tmp;
    tmp=a;
    a=b;
    b=tmp;
}
swap();
document.write("a="+a+",b="+b+"<br/>");


var welcomeString="welcome";
document.write(welcomeString.charAt(2)+"<br/>");
document.write(welcomeString.charAt(6)+"<br/>");

document.write(welcomeString.substring(3)+"<br/>");
document.write(welcomeString.substring(0,6)+"<br/>");

var sentence="shit is shit,shit";
document.write(welcomeString.replace("come","go")+"<br/>");
document.write(sentence.replace(/shit/g,"SD")+"<br/>");

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

document.write(sentence.indexOf("class")+"<br/>");
document.write(sentence.indexOf("shit")+"<br/>");
document.write(sentence.lastIndexOf("shit")+"<br/>");
document.write(sentence.match("is")+"<br/>");
document.write(sentence.match(/shit/g)+"<br/>");
document.write(sentence.search(/shit/g)+"<br/>");

function countChar(stringToCount, char) {
    var charCount = 0;
    
    return charCount;
}
var stringToCount = "Can you can a can as a Canner can can a can";
document.write("There are " + countChar(stringToCount, "c") + " c in " + stringToCount); 


var arr=new Array("America","Greece","Britain","Canada","China","Egypt");
    var  count=0;
    //但是这样有一个问题，就是当他一个单词检测到有a或者A之后就不再继续下去了，得到的结果只有4
    function statistic() {
        for (var i=0;i<arr.length;i++){
            if (arr[i].indexOf("a")!=-1 || arr[i].indexOf("A")!=-1){
                count++;
            }
        }
        document.write(count);
    }

    //把这一个字符串又放到一个数组里去查看是否有aA
    function statistic1() {
        var arrs=new Array();
        for (var i=0;i<arr.length;i++){
            //把arr[i]放入arrs这个数组里
            arrs=arr[i];
            //循环遍历arrs这个数组
            for (var j=0;j<arrs.length;j++){
                //indexOf() 方法可返回某个指定的字符串值在字符串中首次出现的位置。如果没有找到匹配的字符串则返回 -1
                if (arrs[j].indexOf("a")!=-1 || arrs[j].indexOf("A")!=-1){
                    count++;
                }
            }
        }
        document.write(count);
    }


    var arr=["a","b","c","d"];
    document.write(arr+"<br/>");
    document.write(arr[2]+"<br/>");
    arr[1]="ss";
    document.write(arr+"<br/>");
    arr[6]="sr";
    document.write(arr+"<br/>");



function getNum(str) 
{
var num = 0;
for (var i = 0; i < str.length; i++) 
{
var char = str.charAt(i);
if (char != " " && !isNaN(char)) 
{
num++;
}
}
return num;
}
document.write(getNum("5646giabifa1564sdafvasf"));