What are Objects in Javascript ? – Code Samples

Objects created as Variables

// Defining object as a variable
var School = {
    name: "DAV Public School",
    studentsCount: 600,
    admissionOpen: false,
};

School.isAdmissionOpen = function() {
    return this.admissionOpen;
};

School.setAdmissionStatus = function( openOrClosed ) {
    this.admissionOpen = openOrClosed;
};

Objects created using new Object()

In the example below, College is an object type.

// Creating object using new Object()  
var College = new Object();
College.name = "IIT Kharagpur";
College.strength = 3500;
College.admissionStatus = false;
College.isAdmissionOpen = function() {
    return this.admissionStatus;
}
College.setAdmissionStatus = function( status ) {
    this.admissionStatus = status;
}

Objects created using Constructor

In the example below, EducationalInstitution is created using the constructor which implies that different types of educational institutions such as schools, and colleges could be created using this type, EducationalInstitution. The object types are created using new operator such as that shown in the code below. This is unlike previous two cases which can be used to create specific objects.

Also, pay attention to the “prototype” keyword which ensures that the methods such as isAdmissionOpen and setAdmissionStatus can be called on all objects types created using “new EducationalInstitution”. If “prototype” is not used, method defined on one object type could not be called on other object types created using “new EducationalInstitution”.

“Prototype” is also used to implement inheritance.

// Creating Object using Constructor  
function EducationalInstitution( name, strength ) {
    this.name = name;
    this.strength = strength;
    var admissionStatus = false;
}

EducationalInstitution.prototype.isAdmissionOpen = function() {
    return this.admissionStatus;
}

EducationalInstitution.prototype.setAdmissionStatus = function( status ) {
    this.admissionStatus = status;
}

var davPublicSchool = new EducationalInstitution( "DAV Public School", 600 );
davPublicSchool.setAdmissionStatus( true );

var iitKharagpur = new EducationalInstitution( "IIT Kharagpur", 3500 );
iitKharagpur.setAdmissionStatus( false );

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