Javascript class method arguments

Create class with arguments or call its methods separately

In the example above, we created a method, which means that it can be accessed without creating an object of the class, unlike , which can only be accessed by objects: Example An example to demonstrate the differences between and methods : Try it Yourself » You use the keyword for getter methods and for setter methods.

JavaScript Classes

In this tutorial, you will learn about JavaScript classes with the help of examples.

Classes are one of the features introduced in the ES6 version of JavaScript.

A class is a blueprint for the object. You can create an object from the class.

You can think of the class as a sketch (prototype) of a house. It contains all the details about the floors, doors, windows, etc. Based on these descriptions, you build the house. House is the object.

Since many houses can be made from the same description, we can create many objects from a class.

Creating JavaScript Class

JavaScript class is similar to the Javascript constructor function, and it is merely a syntactic sugar.

// constructor function function Person () < this.name = 'John', this.age = 23 >// create an object const person1 = new Person();

Instead of using the function keyword, you use the class keyword for creating JS classes. For example,

// creating a class class Person < constructor(name) < this.name = name; >>

The class keyword is used to create a class. The properties are assigned in a constructor function.

Now you can create an object. For example,

// creating a class class Person < constructor(name) < this.name = name; >> // creating an object const person1 = new Person('John'); const person2 = new Person('Jack'); console.log(person1.name); // John console.log(person2.name); // Jack

Here, person1 and person2 are objects of Person class.

Note : The constructor() method inside a class gets called automatically each time an object is created.

Javascript Class Methods

While using constructor function, you define methods as:

// constructor function function Person (name) < // assigning parameter values to the calling object this.name = name; // defining method this.greet = function () < return ('Hello' + ' ' + this.name); >>

It is easy to define methods in the JavaScript Class. You simply give the name of the method followed by () . For example,

class Person < constructor(name) < this.name = name; >// defining method greet() < console.log(`Hello $`); > > let person1 = new Person('John'); // accessing property console.log(person1.name); // John // accessing method person1.greet(); // Hello John

Note : To access the method of an object, you need to call the method using its name followed by () .

Getters and Setters

In JavaScript, getter methods get the value of an object and setter methods set the value of an object.

Javascript Classes may include getters and setters. You use the get keyword for getter methods and set for setter methods. For example,

class Person < constructor(name) < this.name = name; >// getter get personName() < return this.name; >// setter set personName(x) < this.name = x; >> let person1 = new Person('Jack'); console.log(person1.name); // Jack // changing the value of name property person1.personName = 'Sarah'; console.log(person1.name); // Sarah

Hoisting

A class should be defined before using it. Unlike functions and other JavaScript declarations, the class is not hoisted. For example,

// accessing class const p = new Person(); // ReferenceError // defining class class Person < constructor(name) < this.name = name; >>

As you can see, accessing a class before defining it throws an error.

‘use strict’

Classes always follow ‘use-strict’. All the code inside the class is automatically in strict mode. For example,

class Person < constructor() < a = 0; this.name = a; >> let p = new Person(); // ReferenceError: Can't find variable: a

Note : JavaScript class is a special type of function. And the typeof operator returns function for a class.

class Person <> console.log(typeof Person); // function

Java Examples, Java Math. Math.max (x,y) — return the highest value of x and y Math.min (x,y) — return the lowest value of x and y Math.sqrt (x) — return the square root of x Math.abs (x) — return the absolute (positive) value of x Math.random () — return a random number between 0 and 1. Math Explained.

Create class with arguments or call its methods separately

How JS code should be structered when instantiating new classes inside controller class Main .

A: pass arguments while creating new class — new Options(args) — and let Options ‘s constructor call its own methods.

B: create new class and call the classes’ methods on the object.

Later I’d use properties from Options in another classes.

// A class Main < constructor(options) < this.options = new Options(options); < firstProperty, secondProperty >= this.options; this.another = new Another(firstProperty, secondProperty); > > // B class Main < constructor(options) < this.options = new Options(); const firstProperty = this.options.methodA(options); const secondProperty = this.options.methodB(options); this.another = new Another(); const anotherPropety = this.another.methodA(firstProperty); (. ) >> 

For the purposes of decoupling I would suggest a third option.

//main.js class Main < constructor(options) < this.options = options; // all instances of class would have: this.options.foo = 'bar' >method() < return `$- $` > > // example.js const options = new Options(); const example = new Main(options); console.log(example.method()); 

This lets your inject your dependencies into a given class, which makes writing tests for your code far simpler. It also gives you the benefit of (as long as you maintain a common interface) swapping out Options for NewAwesomeOptions at some later point without having to find everywhere you might have hard coded it into a class.

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Java Class Methods

Java Class Methods

You learned from the Java Methods chapter that methods are declared within a class, and that they are used to perform certain actions:

Example

Create a method named myMethod() in Main:

myMethod() prints a text (the action), when it is called . To call a method, write the method’s name followed by two parentheses () and a semicolon ;

Example

Inside main , call myMethod() :

public class Main < static void myMethod() < System.out.println("Hello World!"); >public static void main(String[] args) < myMethod(); >> // Outputs "Hello World!" 

Static vs. Non-Static

You will often see Java programs that have either static or public attributes and methods.

In the example above, we created a static method, which means that it can be accessed without creating an object of the class, unlike public , which can only be accessed by objects:

Example

An example to demonstrate the differences between static and public methods :

public class Main < // Static method static void myStaticMethod() < System.out.println("Static methods can be called without creating objects"); >// Public method public void myPublicMethod() < System.out.println("Public methods must be called by creating objects"); >// Main method public static void main(String[] args) < myStaticMethod(); // Call the static method // myPublicMethod(); This would compile an error Main myObj = new Main(); // Create an object of Main myObj.myPublicMethod(); // Call the public method on the object >> 

Note: You will learn more about these keywords (called modifiers) in the Java Modifiers chapter.

Access Methods With an Object

Example

Create a Car object named myCar . Call the fullThrottle() and speed() methods on the myCar object, and run the program:

// Create a Main class public class Main < // Create a fullThrottle() method public void fullThrottle() < System.out.println("The car is going as fast as it can!"); >// Create a speed() method and add a parameter public void speed(int maxSpeed) < System.out.println("Max speed is: " + maxSpeed); >// Inside main, call the methods on the myCar object public static void main(String[] args) < Main myCar = new Main(); // Create a myCar object myCar.fullThrottle(); // Call the fullThrottle() method myCar.speed(200); // Call the speed() method >> // The car is going as fast as it can! // Max speed is: 200 

Example explained

1) We created a custom Main class with the class keyword.

2) We created the fullThrottle() and speed() methods in the Main class.

3) The fullThrottle() method and the speed() method will print out some text, when they are called.

4) The speed() method accepts an int parameter called maxSpeed — we will use this in 8) .

5) In order to use the Main class and its methods, we need to create an object of the Main Class.

6) Then, go to the main() method, which you know by now is a built-in Java method that runs your program (any code inside main is executed).

7) By using the new keyword we created an object with the name myCar .

8) Then, we call the fullThrottle() and speed() methods on the myCar object, and run the program using the name of the object ( myCar ), followed by a dot ( . ), followed by the name of the method ( fullThrottle(); and speed(200); ). Notice that we add an int parameter of 200 inside the speed() method.

Remember that..

The dot ( . ) is used to access the object’s attributes and methods.

To call a method in Java, write the method name followed by a set of parentheses () , followed by a semicolon ( ; ).

A class must have a matching filename ( Main and Main.java ).

Using Multiple Classes

Like we specified in the Classes chapter, it is a good practice to create an object of a class and access it in another class.

Remember that the name of the java file should match the class name. In this example, we have created two files in the same directory:

Main.java

public class Main < public void fullThrottle() < System.out.println("The car is going as fast as it can!"); >public void speed(int maxSpeed) < System.out.println("Max speed is: " + maxSpeed); >> 

Second.java

When both files have been compiled:

JavaScript | Function Parameters, Output: Arguments Pass by Value: In a function call the parameters are called as arguments. The pass by value sends the value of variable to the function. It does not sends the address of variable. If the function changes the value of arguments then it does not affect the original value. Example:

Methods in classes js

Javascript Class Methods

// constructor function function Person (name) < // assigning parameter values to the calling object this.name = name; // defining method this.greet = function () < return ('Hello' + ' ' + this.name); >>

Class and methods in javascript Code Example, class Rectangle < constructor(height, width) < this.height = height; this.width = width; >// Getter get area() < return this.calcArea(); >// Method calcArea

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