Startseite JavaScript Archive nach Kategorien "Klassen und Objekte" (Seite 2)

Kategorie: Klassen und Objekte

[JavaScript] DOM: Buttonklick realisieren 

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0;">
  <title>DOM Buttonclick</title>
  <script>
  // Strict mode
  'use strict';

  // https://wiki.selfhtml.org/wiki/JavaScript/Module_und_Kapselung
  // private Scope deklarieren
  // anonyme Funktion 1
  (
      // anonyme Funktion 2
    function ()
    {
      // Initialisierung
      function init() {
        let btn = document.getElementById('btnTestButton');

        if (btn) {
          btn.addEventListener(
            "click",
            function () { txtout(); }
          );
        }
      }

      // Textausgabe
      function txtout() {
        let txt = document.getElementById("textfeld");
        if (txt) {
          txt.innerHTML = "Test1";
        }
      }

      // Event-Listener
      document.addEventListener(
        "DOMContentLoaded",
        function () { init(); }
      );
    }
    
    // Aufruf der inneren anonymen Funktion 2
    ()
  );
  </script>
</head>
<body>
    <p>Button klicken!</p>
    <button type="button" id="btnTestButton">Klick!</button>
    <div id="textfeld"></div>
</body>
</html>

[JavaScript] Fortgeschrittene Objektdefinition: Revealing Module Pattern (Kapselung plus öffentliche Schnittstelle) 

// https://wiki.selfhtml.org/wiki/JavaScript/Module_und_Kapselung

// Klasse / Modul definieren
// Grundmodul
let oModule = (function() {
  // private
  let priv1 = 100;
  let priv2 = 200;
   
  function priv_func1(var1, var2) {
    return var1 + var2 + priv1;
  }
 
  function priv_func2(var1, var2) {
    return var1 + var2 + priv2;
  }
   
  // public 
  return {
    public_func1: function(var1, var2) {
      return priv_func1(var1, var2) + priv_func2(var1, var2);
    }
  };
 
})();

// Erweiterung des Grundmoduls um public und private Methoden
(function (module) {
  // private
  let priv3 = 200;
  
  function priv_func3(var1, var2) {
    return var1 + var2 + priv3;
  }
  
  // public
  module.public_func2 = function(var1, var2) {
    return priv_func3(var1, var2);
  };
})(oModule);

// ok -> 306
console.log(oModule.public_func1(1, 2));
// ok -> 203
console.log(oModule.public_func2(1, 2));
// undefined
console.log(oModule.priv1);
// undefined
console.log(oModule.priv3);
// "error"
console.log(oModule.priv_func1(1, 2));
// "error"
console.log(oModule.priv_func3(1, 2));

[JavaScript] Klassendeklaration über “function”

Variante 1 (public)

// https://www.phpied.com/3-ways-to-define-a-javascript-class/
// https://developer.mozilla.org/de/docs/Web/JavaScript/Introduction_to_Object-Oriented_JavaScript

// Klasse Person über "function" abbilden
function Person(vorname, nachname, alter) {
  this.Vorname = vorname;
  this.Nachname = nachname;
  this.Alter = alter;
  this.getText = function(type){
    var text = "";
     
    switch (type) {
      case "1":
        text = this.Vorname;
        break;
      case "2":
        text = this.Nachname;
        break;
      case "3":
        text = this.Alter;
        break;
      default:
        text = "-";
        break;
    }
     
    return text;
  };
}

var p = new Person("Udo", "Mustermann", 30);

// Datenausgabe
console.log(p.getText("1"));

Variante 2 (private und public)

function User() {

  // private
  a = 1;
  
  function private() {
    return a;
  }

  // public
  this.b = 2;

  this.public = function() {
    return this.b;
  };
}

let u = new User();
// error
//u.private();
// undefined
console.log(u.a);
// 2
console.log(u.b);
// 2
console.log(u.public());

[JavaScript] Einfache Objektdefinition

einfache Objektdefinition mit Literalen

// https://www.w3schools.com/js/js_objects.asp
// https://www.phpied.com/3-ways-to-define-a-javascript-class/

let person = {
  Vorname: "Horst",
  Nachname: "Mustermann",
  Alter: 65,
  getText: function(type){
    let text = "";
     
    switch (type) {
      case "1":
        text = this.Vorname;
        break;
      case "2":
        text = this.Nachname;
        break;
      case "3":
        text = this.Alter;
        break;
      default:
        text = "-";
        break;
    }
     
    return text;
  }
};

// Horst -> Klaus
person["Vorname"] = "Klaus";

// Datenausgabe
console.log(person.Vorname);
console.log(person["Vorname"]);
console.log(person.getText("1"));
console.log(person.getText("2"));
console.log(person.getText("3"));

einfache Objektdefinition mit new Object

let person = new Object();

person.Vorname = "Horst";
person.Nachname = "Mustermann";
person.Alter = 65;
person.getText = function(type){
  let text = "";
   
  switch (type) {
    case "1":
      text = this.Vorname;
      break;
    case "2":
      text = this.Nachname;
      break;
    case "3":
      text = this.Alter;
      break;
    default:
      text = "-";
      break;
  }
   
  return text;
};
 
// Datenausgabe
console.log(person.Vorname);
console.log(person["Vorname"]);
console.log(person.getText("1"));
console.log(person.getText("2"));
console.log(person.getText("3"));

alternative Objektdefinition mit new Object + Literalen

let person = new Object({
  Vorname : "Horst",
  Nachname : "Mustermann",
  Alter : 65,
  getText : function(type){
      let text = "";
       
      switch (type) {
        case "1":
          text = this.Vorname;
          break;
        case "2":
          text = this.Nachname;
          break;
        case "3":
          text = this.Alter;
          break;
        default:
          text = "-";
          break;
      }
       
      return text;
  }
});

// Datenausgabe
console.log(person.Vorname);
console.log(person["Vorname"]);
console.log(person.getText("1"));
console.log(person.getText("2"));
console.log(person.getText("3"));