arguments,foreach循環,重載,回調函數,對象繼承

時間 2019-11-11

標籤 arguments foreach 循環重載函數對象繼承欄目軟件設計简体版

原文原文鏈接

<html>

<body>

   <p id="p"> this is ppp </p>
   <p id="p2"> this is ppp22 </p>
   <p id="p3"> this is ppp33 </p>
   <script>
   //arguments
   //arguments是每個函數內部的一個對象
   //能夠訪問實際傳遞給函數的參數的信息。

   /*
   function add(a,b){
       //console.log(add.length);//形參的個數
       //console.log(arguments.length);//實際傳過來的參數
       var total = 0;
       for(var i = 0;i< arguments.length;i++){

           total += arguments[i];
       }
       return total;
   }

   var result = add(1,2,3,4,5);
   var result2 = add(1,2);
   console.log(result);
   console.log(result2);


   function setStyle(){
       if(arguments.length < 1
           || arguments.length > 2){
           return ;
       }


       var pele = document.getElementById("p");
       if(arguments.length == 1){
           return pele.style[arguments[0]] ;
       }else{
           pele.style[arguments[0]] = arguments[1];
           //pele.style.backgroundColor = "red"
       }


   }

   //setStyle("fontSize","18px");

   setStyle("backgroundColor","red");
   var styleValue = setStyle("backgroundColor");
   alert(styleValue);

   setStyle("fontSize","18px");
   var styleValue2 = setStyle("fontSize");
   alert(styleValue2);

   //聲明的時候參數的個數與實際調用時無關


   //foreach循環
   var arr = [100,300,800];
   for(var data in arr){
       //alert(arr[data]); //循環數組時，data是下標
   }

   var o ={name:"cj",age:22};
   for(var p in o){
       //alert(p);
       //alert(o[p]);
   }


   function myForEach(eles,callback){
       for(var i=0;i< eles.length;i++){

           callback(i,eles[i]);
       }
   }

   var alls = document.getElementsByTagName("p");
   myForEach(alls,function(index,ele){
       //alert(index);
       //alert(ele);
       ele.style.backgroundColor = "red";
   });*/







   //重載（個數不一樣，類型不一樣)
   /*
   function prop(){

       var firstP = document.getElementById("p");

       if(arguments.length == 1){
           var temp = arguments[0];

           for(p in temp) {
               firstP.style[p] = temp[p];
           }


       }else if(arguments.length == 2) {

           firstP.style[arguments[0]] = arguments[1];

       }


   }

   //prop("backgroundColor","black");
   //prop("fontSize","38px");
   prop({
       backgroundColor:"red",
       fontSize:"38px"
   });

   */

   /*



   */
   //回調函數
   //js裏面，狹隘的理解，參數做爲參數，並在函數
   //實現體裏面被調用

   /*
   function a(){
       b(); //c();d();
   }
   function a(callback){

       callback();

   }
   function b(){

   }

   function c(){

   }
   a(b);
   a(c);
   a(function(){});

   function CjOneDay(maiyan){
       console.log("chouyan");

       var yan = maiyan(10);
       console.log(yan);
   }

   function banZhangMaiYan(money){
       if(money == 20){
           return "wuyeshen";
       }else{
           return "zhongnanhai";
       }
   }
   CjOneDay(banZhangMaiYan);


   //
   function myForEachBgColor(eles){

       for(var i=0;i< eles.length;i++){

           if(i % 2 == 0 ) {
               eles[i].style.backgroundColor = "red";
           }else{
               eles[i].style.backgroundColor = "green";
           }
       }
   }

   function myForEachFontSize(eles){

       for(var i=0;i< eles.length;i++){

           if(i % 2 == 0 ) {
               eles[i].style.fontSize = "30px";
           }else{
               eles[i].style.fontSize = "10px";
           }
       }
   }

   function myForEach(eles,callback){

       for(var i=0;i< eles.length;i++){

           callback(i,eles[i]);
       }
   }
   var allp = document.getElementsByTagName("p");
   //myForEachBgColor(allp);
   //myForEachFontSize(allp);


   myForEach(allp,function(index,ele){
       if(index % 2 == 0 ) {
               ele.style.fontSize = "30px";
           }else{
               ele.style.fontSize = "10px";
           }
   });

   myForEach(allp,function(index,ele){
       if(index % 2 == 0 ) {
               ele.style.backgroundColor = "yellow";
           }else{
               ele.style.backgroundColor = "green";
           }
   });

   */


       //對象繼承
       var child ={name:"banzhang"};
       var parent = {age:18,gender:true}

       function myExtend(cObject,pObject) {

           for(var p in pObject){

               cObject[p] = pObject[p];
           }
           return cObject;
       }

       var exChild = myExtend(child,parent);
       //alert(exChild);
       console.log(exChild);

       var exChild = superExtend(child,parent,p2,p3,p4);

   </script>
</body>
</html>html