CODEWITHSUNDEEP
javascript
Nithin B
Nithin B

Reputation: 680

How to access static property of constructor in java-script using instance variable of constructor?

I have created a class(constructor) in java-script as given below which has a property of type static.

function MyClass(property1 )
{
    this.Property1 = property1 || "";
}

MyClass.StaticProperty = {
    Running: "Running",
    NotRunning: "NotRunning"
}

Now I can access the above static property using constructor name as below:

MyClass.StaticProperty.Running

But I also want to access the property using an instance of the constructor as below:

var myClassInstance = new MyClass("value");
var status = myClassInstance.StaticProperty.Running;

I am aware that I can access if it is a prototype variable or variable defined inside the constructor. But I don't want to do that because I want it to behave as a static variable.

Use case:

I am having multiple constructors with the same property name. I am getting these constructor instances in the array. I want to loop through each constructor in an array and read the static variable. For example

var allStaticPropertyValues = [];
for(index = 0; index < arrayOfConstructors.length; index++)
{
    for(var property in arrayOfConstructors[index].StaticProperty)
    {
        allStaticPropertyValues.push(arrayOfConstructors[index].StaticProperty[property]);
    }
}

What I tried:

  1. I tried to get class Type using typeof keyword but it is giving only as an object, not constructor reference that I can use to access the property.

  2. instanceOfObject.constructor.getname() which will give the name of the constructor as a string and not as a reference.

Upvotes: 1

Views: 1326

Answers (2)

Maheer Ali
Maheer Ali

Reputation: 36564

You can use constructor property of instance of the MyClass to get MyClass and then you can access the static variables of MyClass

function MyClass(property1 )
{
    this.Property1 = property1 || "";
}

MyClass.StaticProperty = {
    Running: "Running",
    NotRunning: "NotRunning"
}

var myClassInstance = new MyClass("value");
var status = myClassInstance.constructor.StaticProperty.Running;

console.log(status)

Upvotes: 2

CertainPerformance
CertainPerformance

Reputation: 370679

Accessing the constructor property will give you a direct reference to the constructor (the object, not as a string), so you can then just access its StaticProperty property:

function MyClass(property1 ){
    this.Property1 = property1 || "";
}
MyClass.StaticProperty = {
    Running: "Running",
    NotRunning: "NotRunning"
}
var myClassInstance = new MyClass("value");


var status = myClassInstance.constructor.StaticProperty.Running;
console.log(status);

Upvotes: 1

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