JavaScript Static Variables

JavaScript Static Variables | When defining a static method or static attribute of a class, the word “Static” is used. A static method has the advantage of eliminating the requirement to create a class instance or object. It doesn’t have a range of values. It will have a single static value that is set up front.

The word “static” is comparable to the word “const.” These kinds of variables have a global presence and scope and are set at run time during startup. These static variables are available for use throughout the script. 

JavaScript’s static keyword is used to specify a class’s static methods or properties. We don’t need to make an instance or object of the class in order to call the static method.

JavaScript Static Variables Example

JavaScript static variables:- To declare a static variable in JavaScript, we can use the static keyword, similar to how a constant variable is defined with the const keyword. Such a type of variable functions as a global variable and is set at run time. The static variable is universal. Unlike the constant variable, the static variable’s value can be changed.

We construct a static variable in JavaScript for several reasons, including replication prevention, fixed-configuration support, and cache support. Also see:- Dynamic Variable Name in JavaScript

Example 1: In the example that follows, a static variable will be created and shown on the JavaScript console.

class Test {
    static staticVariable = "Hello";
    static staticMethod() {
        console.log("Static variable value: " + this.staticVariable);
        return "Static method is initiated.";
    }
}

console.log(Test.staticVariable);
console.log(Test.staticMethod());

As we can see from the program code above, a class contains a static method that, when called, calls a statement inside the class’s static method. Below is the result of the following:-

Output:-

Hello
Static variable value: Hello
Static method is initiated.

We can even modify the JavaScript static variables. In the below program, a static variable is initialized in the Test class and later we modified it outside the class.

class Test {
    static staticVariable = "Hello";
}

console.log(Test.staticVariable);
Test.staticVariable = "Hi";
console.log(Test.staticVariable);

Output:-

Hello
Hi

Using JavaScript const Variable

Example 2:- Here is an example of how to use the JavaScript const keyword in practice:

const value = 2;
try {
    value = 4;
}
catch (e) {
    console.log(e.toString());
}

console.log(value);

The const variable is given a value in the code above, but when we attempt to assign a different value, an error is raised, indicating that the value designated as const cannot be modified. The result of the code above is thus:-

Output:-

TypeError: Assignment to constant variable.
2

We learned in this section that static and const variables serve different functions and serve different roles. A static variable may be used for a class property or method, whereas a const variable may be used to initialize a const value for an object, variable, or array.

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