Javascript for Java Developers

01-object-example.js

// create an empty object - no class was needed !!
var superhero = {};
 
superhero.name = 'Superman';  
superhero.strength = 100;

02-map-example.js

Map<String,Object> superhero = new HashMap<>();
 
superhero.put("name","Superman");  
superhero.put("strength", 100);

03-functions-are-just-values.js

var flyFunction = function() {  
    console.log('Flying like a bird!');
};
 
superhero.fly = flyFunction;

04-fly.js

// prints 'Flying like a bird!' to the console
superhero.fly();

05-interface.java

public interface Power {  
    void use();
}
 
public class SuperHero {
 
    private Power flyPower;
 
    public void setFly(Power flyPower) {
        this.flyPower = flyPower;
    }
 
    public void fly() {
        flyPower.use();
    }
}

06-java8-equivalent.java

// Java 7 equivalent
Power flyFunction = new Power() {  
    @Override
    public void use() {
        System.out.println("Flying like a bird ...");
    }
};
 
// Java 8 equivalent 
superman.setFly(  
    ()->System.out.println("Flying like a bird ..."));
 
superman.fly();

07-this-keyword.js

var superman = {
 
  heroName: 'Superman',  
 
  sayHello: function() {
      console.log("Hello, I'm " + this.heroName );
  }  
};
 
superman.sayHello();  

08-pass-function.js

var failThis = superman.sayHello;
 
failThis();

09-override-this.js

// overrides 'this' with superman
hello.call(superman);  

10-prototype.js

var avengersHero = {  
    editor: 'Marvel'
};
 
var ironMan = {};
 
ironMan.__proto__ = avengersHero;
 
console.log('Iron Man is copyrighted by ' + ironMan.editor);

11-constructor-functions.js

function SuperHero(name, strength) {  
    this.name = name;
    this.strength = strength;
}

12-java-inheritance.js

avengersHero.editor = 'DC Comics'; 

13-constructor-functions.js

var superman = new SuperHero('Superman', 100);
 
console.log('Hello, my name is ' + superman.name); 

14-prototypical-inheritance.js

function SuperHero(name, strength) {  
    this.name = name;
    this.strength = strength;
}
 
SuperHero.prototype.sayHello = function() {  
    console.log('Hello, my name is ' + this.name);
}
 
var superman = new SuperHero('Superman', 100);  
superman.sayHello(); 

15-alternative-to-new.js

var superHeroPrototype = {  
   sayHello: function() {
        console.log('Hello, my name is ' + this.name);
    } 
};
 
var superman = Object.create(superHeroPrototype);  
superman.name = 'Superman';

16-closures-vs-lambdas.java

public interface FlyCommand {  
    public void fly();
}
 
public class FlyingHero {
 
    private String name;
 
    public FlyingHero(String name) {
        this.name = name;
    }
 
    public void fly(FlyCommand flyCommand) {
        flyCommand.fly();
    }
}

17-fly-command.java

String destination = "Mars";  
superMan.fly(() -> System.out.println("Flying to " +  
    destination ));
    
    

18-closures.js

var destination = 'Mars';
 
var fly = function() {  
    console.log('Fly to ' + destination);
}
 
fly(); 

19-modules.js

function createHero(heroName) {
 
    var name = heroName;
 
    return  {
        fly: function(destination) {
          console.log(name + ' flying to ' + destination);
        }
    }; 
}

20-closures-encapsulation.js

var superman = createHero('SuperMan');
 
superman.fly('The Moon');

21-block-scoping.js

function counterLoop() {
 
    console.log('counter before declaration = ' + i); 
 
    for (var i = 0; i < 3 ; i++) {
        console.log('counter = ' + i); 
    }
 
    console.log('counter after loop = ' + i); 
}
 
counterLoop();  

22-counter-loop.js

function counterLoop() {
 
    var i; // i is 'seen' as if declared here! 
 
    console.log('counter before declaration = ' + i); 
 
    for (i = 0; i < 3 ; i++) {
        console.log('counter = ' + i); 
    }
 
    console.log('counter after loop:  ' + i); 
}

32-hosting-sees.js

function counterLoop() {
 
    var i; // i is 'seen' as if declared here! 
 
    console.log('counter before declaration = ' + i); 
 
    for (i = 0; i < 3 ; i++) {
        console.log('counter = ' + i); 
    }
 
    console.log('counter after loop:  ' + i); 
}

In 09-override-this.js

hello.call(superman);

should be

failThis.call(superman);