Question

我在函数内部创建了一个对象。我想在一个中调用对象方法言。

＆＃13;

(function(){
        s4 = function(getSection){
            var self = {
            name: function(getname){
                console.log("Name of the Student " +getname);
            },

            subject: function(getsub){
                console.log(" & Studying " +getsub);
            }

        }
     return self;   
        }
    })();

＆＃13;

 <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Student Details</title>
</head>
<body>
  <div class="hello">
      <h1>Student Details</h1>
  </div>
    <script src="script.js"></script>
    <script>
        s4("5th").name("John"); //This works fine
        s4("5th").subject("Python"); //This works fine
        s4("5th").name("John").subject("Python"); //Shows error: SCRIPT5007: Unable to get property 'subject' of undefined or null reference


    </script>
</body>
</html>

＆＃13;

当我致电s4("5th").name("John").subject("Python");时显示错误：

SCRIPT5007：无法获得财产＆＃39; subject＆＃39;未定义或空引用

请帮我解决这个问题。提前谢谢。

Answer 1

在您的方法中，返回对象。 return this和name中的subject.这称为方法链接，它通过返回对象来工作。

＆＃13;

(function() {
  s4 = function(getSection) {
    var self = {
      name: function(getname) {
        console.log("Name of the Student " + getname);
        return this;
      },
      subject: function(getsub) {
        console.log(" & Studying " + getsub);
        return this;
      }
    }
    return self;
  }
})();

s4("5th").name("John");
s4("5th").subject("Python");
s4("5th").name("John").subject("Python");

＆＃13;

Answer 2

这称为method chaining，通常通过使每个函数不返回其他值return this;来实现：

name: function(getname){
    console.log("Name of the Student " +getname);
    return this;
},

subject: function(getsub){
    console.log(" & Studying " +getsub);
     return this;
}

然后s4("5th").name("John").subject("Python");将有效，因为name("John")会返回s4("5th")的结果。

Answer 3

您的代码应为

(function() {
  s4 = function(getSection) {
    var self = {
      name: function(getname) {
        console.log("Name of the Student " + getname);
        return this;
      },
      subject: function(getsub) {
        console.log(" & Studying " + getsub);
        return this;
      }
    }
    return self;
  }
})();
<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <title>Student Details</title>
</head>

<body>
  <div class="hello">
    <h1>Student Details</h1>
  </div>
  <script src="script.js"></script>
  <script>
    s4("5th").name("John"); //This works fine
    s4("5th").subject("Python"); //This works fine
    s4("5th").name("John").subject("Python"); //Shows error: SCRIPT5007: Unable to get property 'subject' of undefined or null reference
  </script>
</body>

</html>

现在你不会因调用函数subject()

而出错

Answer 4

你的功能

name: function(getname){
        console.log("Name of the Student " +getname);
    }

不会返回this。将其更改为：

name: function(getname){
        console.log("Name of the Student " +getname);
        return this;
    }

如何在一个语句中调用JavaScript对象方法（方法链接）

4 个答案: