当前位置：网站首页>How to implement overloading in JS

How to implement overloading in JS

2022-06-12 20:35:00 【Stand on the bridge and bake cold noodles】

What is overload ?

Same function name , Multiple functions with different parameter lists , It can be called according to the different values of the arguments passed in , Execute different logic .

benefits : Reduce the number of function names , Lighten the burden on the caller

How to achieve it ?

stay JS Two functions with the same name are forbidden to exist at the same time , If they exist at the same time , The functions defined later will override the previous functions ,

Can use arguments To solve .

What is? arguments？

Function , You don't have to define it , It is an array of class objects .

What is a class array ？ Looks like an array , With subscript , Yes length attribute , It can also cycle . The difference is that the array is Array Object of type , Class array is Object object . Class arrays do not have permission to use array methods

How to overload ？

  1. Define only one function , No parameters are required
  2. Inside the function , Judge arguments The length of , Element value , Element type and other conditions , Different logic is executed according to different actual parameter values 
    <!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    function pay(              ){
    // arguments[              ].length
    //              0      1...
      if(arguments.length==0){
        console.log(` Mobile payment ...`)
      }else if(arguments.length==1){
        console.log(` cash payment , Take you ${arguments[0]} element `)
      }else{
        if(arguments[1]=="123456"){
          console.log(` Pay by credit card , From your card number ${arguments[0]} Deduction successful !`)
        }else{
          console.log(` Pay by credit card , Incorrect password `);
        }
      }
    }

    pay();
    pay(100);
    pay("6553 1234","123456");
    pay("6553 1234","12345");
  </script>
</body>
</html>
 Running results : 
 Mobile payment ...
 cash payment , Take you 100 element 
 Pay by credit card , From your card number 6553 1234 Deduction successful !
 Pay by credit card , Incorrect password

原网站

版权声明
本文为[Stand on the bridge and bake cold noodles]所创，转载请带上原文链接，感谢
https://yzsam.com/2022/163/202206122029152027.html

边栏推荐

猜你喜欢

随机推荐