Question

我很难学习构造函数和原型。我要做的就是在构造中添加2个新对象，然后显示对象的每个部分。在我的示例中，我想添加两个对象和控制台日志，每个名称，地址和gpa。

构造函数：

var Students = function(name, street, city, state, gpa) {
   this.student = {
      name: name,
      address: {
         street: street,
         city: city,
         state: state
      },
      gpa: gpa};
   this.array = [];
   this.array.push(this.student);
};

Students.prototype = {
   init: function(name, street, city, state, gpa) {
      this.student = {
         name: name,
         address: {
            street: street,
            city: city,
            state: state
         },
         gpa: gpa
      };
      this.array = [];
      this.array.push(this.student);
      console.log(this.array);
   },
   test: function() {
      console.log(this.array);
      for (i = 0; i < this.array.length; i++) {
         i = i % this.array.length;
         var studentTotal = 0;
         //This will loop through gpa array
         for (j = 0; j < this.array[i].gpa.length; j++) {
            studentTotal += this.array[i].gpa[j];
         }

         this.array[i].myAvg = studentTotal / this.array[i].gpa.length;
         this.array[i].gpaAverage = this.array[i].myAvg;
         console.log("Name: " + this.array[i].name);
         console.log("Address: " + this.array[i].address.street + ' ' +
                 this.array[i].address.city + ' ' +
                 this.array[i].address.state);
         console.log("GPA: " + this.array[i].gpa);
         console.log("Average: " + this.array[i].gpaAverage);
         console.log(new Date());
      }
   }
};

main.js：

var stud1 = [
   new Students(
           "Walker",
           '123 South Drive',
           'Sarasota',
           'FL',
           [
              3.0,
              3.4,
              3.8
           ]),
   new Students(
           'Christian',
           '5601 Pebble Beach Ln',
           'Sacromento',
           'CA', [
      2.5, 3.6, 3.8
   ])];

stud1.test();

Answer 1

你正在构建一系列学生。

var stud1 = [...]正在创建一个Students数组我想你最好将Students函数重命名为Student（因为它只构建一个学生）并将您的数组stud1重命名为studentArray，以使事情更容易理解。

然后，如果您想要对阵列中的所有学生拨打test()，请使用：

for(var i=0; i<studentArray.length; i++){
   studentArray[i].test();
}

在其他作品中，您尝试在数组上使用方法test()，并且数组没有该功能，学生也可以。

修改

考虑到您的评论，您可以制作另一个可以跟踪创建的学生的对象，并作为新学生的工厂。这封装了学生创建逻辑，并将所有学生列为学生构建逻辑，并让您进一步了解javascript对象的构建。

此外，让您的学生负责了解他们的平均GPA，因为您已经让他们跟踪他们的个人GPA。所以添加一个函数getAverageGPA()，然后每当你想要打印学生时，调用函数print()，打印出所有信息并获得他们的平均GPA。

由于您希望每次创建新学生时都这样做，请让学生工厂（School）为您执行此操作。

<强>学生：学生班，其中包含有关学生的所有信息以及打印他/她的功能以及获得他们的平均GPA。

/** * Student Object * @param {String} name * @param {String} street * @param {String} city * @param {String} state * @param {Array} gpa * @returns {Student} */ var Student = function(name, street, city, state, gpa) { this.name = name; this.address = { street: street, city: city, state: state }; this.gpa = gpa; }; Student.prototype = { /** * Function to print the student and their average GPA * @returns {undefined} */ print: function() { console.log("Name: " + this.name); console.log("Address: " + this.address.street + " " + this.address.city + " " + this.address.state); console.log("Average GPA: " + this.getAverageGPA()); }, /** * Function to find a students average GPA * @returns {Number} */ getAverageGPA: function() { var avgGPA = 0; for (var j = 0; j < this.gpa.length; j++) { avgGPA = avgGPA + this.gpa[j]; } avgGPA = avgGPA / this.gpa.length; return avgGPA; } };

<强>学校：持有学生并负责创建和打印它们的课程

/** * Object to encapsulate student creation while * keeping track of all created students * @returns {School} */ function School() { /** * Array of all the students created so far * @type Array */ this.createdStudents = []; } School.prototype = { /** * Function to add a student to the list of students * @param {Student} newStudent * @returns {undefined} */ addStudent: function(newStudent) { this.createdStudents.push(newStudent); this.printScores(); }, /** * Function to create a student, add it to the list, and return it * @param {String} name * @param {String} street * @param {String} city * @param {String} state * @param {Array} gpa * @returns {Student} */ createStudent: function(name, street, city, state, gpa) { var newStudent = new Student(name, street, city, state, gpa); this.addStudent(newStudent); return newStudent; }, /** * Print out all the students and their scores * @returns {undefined} */ printScores: function() { for (var i = 0; i < this.createdStudents.length; i++) { this.createdStudents[i].print(); } } };

主要测试学生的创作是什么？

/** * The Factory to hold students * @type School */ var school = new School(); // Student created yourself that you have access to in main var standAloneStudent = new Student( "Bob", "555 Nowhere street", "Timbucktue", "AL", [ 4.0, 4.0, 4.0 ]); // You can get the students GPA without going through the factory console.log("My student's GPA is: " + standAloneStudent.getAverageGPA()); console.log(""); // How to add a student that you create yourself school.addStudent(new Student( 'Christian', '5601 Pebble Beach Ln', 'Sacromento', 'CA', [ 2.5, 3.6, 3.8 ])); console.log(""); // How to create a student through the factory school.createStudent( "Walker", '123 South Drive', 'Sarasota', 'FL', [ 3.0, 3.4, 3.8 ]); // You can also get the students GPA through the school // (However, you may want to make a set instead of an array so you can key // off of a student's name or maybe ID) console.log("My student's GPA is: " + school.createdStudents[0].getAverageGPA());

这应该给你输出：

My student's GPA is: 4 Name: Christian Address: 5601 Pebble Beach Ln Sacromento CA Average GPA: 3.2999999999999994 Name: Christian Address: 5601 Pebble Beach Ln Sacromento CA Average GPA: 3.2999999999999994 Name: Walker Address: 123 South Drive Sarasota FL Average GPA: 3.4 My student's GPA is: 3.2999999999999994

javascript中的构造函数和原型

1 个答案: