JavaScript Getter (The get Keyword)
This example uses a lang
property to get
the value of the language
property.
Example(1)
<script> // Create an object: var person = { firstName: "Megha", lastName : "Doe", language : "en", get lang() { return this.language; } }; // Display data from the object using a getter: document.getElementById("demo1").innerHTML = person.lang; </script>
JavaScript Setter (The set Keyword)
This example uses a lang
property to set
the value of the language
property.
Example(2)
<script> // Create an object: var person = { firstName: "Megha", lastName : "Doe", language : "en", get lang() { return this.language; } }; // Set an object property using a setter: person.lang = "en"; // Display data from the object: document.getElementById("demo2").innerHTML = person.language; </script>
Example 3
<script> var person = { firstName: "John", lastName : "Doe", fullName : function() { return this.firstName + " " + this.lastName; } }; // Display data from the object using a method: document.getElementById("demo").innerHTML = person.fullName(); </script>
Example 4
<script> var person = { firstName: "John", lastName : "Doe", get fullName() { return this.firstName + " " + this.lastName; } }; // Display data from the object using a getter: document.getElementById("demo").innerHTML = person.fullName; </script>
Example 3 access fullName as a function: person.fullName().
Example 4 access fullName as a property: person.fullName.
The second example provides simpler syntax.
Data Quality
JavaScript can secure better data quality when using getters and setters.
Using the lang
property, in this example, returns the value of the language
property in upper case:
<script> // Create an object: var person = { firstName: "John", lastName : "Doe", language : "en", get lang() { return this.language.toUpperCase(); } }; // Display data from the object using a getter: document.getElementById("demo").innerHTML = person.lang; </script>
Using the lang
property, in this example, stores an upper case value in the language
property:
Example(7)
<script> var person = { firstName: "John", lastName : "Doe", language : "", set lang(lang) { this.language = lang.toUpperCase(); } }; // Set an object property using a setter: person.lang = "en"; // Display data from the object: document.getElementById("demo").innerHTML = person.language; </script>
Why Using Getters and Setters?
It gives simpler syntax
It allows equal syntax for properties and methods
It can secure better data quality
It is useful for doing things behind-the-scenes
Object.defineProperty()
The Object.defineProperty()
method can also be used to add Getters and Setters:
Example(8)
<script> // Define an object var obj = {counter : 0}; // Define Setters and Getters Object.defineProperty(obj, "reset", { get : function () {this.counter = 0;} }); Object.defineProperty(obj, "increment", { get : function () {this.counter++;} }); Object.defineProperty(obj, "decrement", { get : function () {this.counter--;} }); Object.defineProperty(obj, "add", { set : function (value) {this.counter += value;} }); Object.defineProperty(obj, "subtract", { set : function (value) {this.counter -= value;} }); // Play with counter: obj.reset; obj.add = 5; obj.subtract = 1; obj.increment; obj.decrement; document.getElementById("demo").innerHTML = obj.counter; </script>
<!DOCTYPE html> <html> <head> <title>How To Use Object Accessors In JavaScript With Example</title> <meta charset="utf-8"> <meta name="viewport" content="width=device-width, initial-scale=1"> <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css"> </head> <style> body{ background: black; } </style> <body> <div class="container"> <br> <div class="text-center"> <h1 id="color" style="color: White">How To Use Object Accessors In JavaScript With Example</h1> </div> <br> <br> <div class="well"> <h2 id="demo1"></h2> <h2 id="demo2"></h2> <script> // Create an object: var person = { firstName: "Megha", lastName : "Doe", language : "English", get lang() { return this.language; } }; // Display data from the object using a getter: document.getElementById("demo1").innerHTML = person.lang; // Set an object property using a setter: person.lang = "en"; // Display data from the object: document.getElementById("demo2").innerHTML = person.language; </script> </div> </div> </body> </html>