Javascript Const And How To Use It

In JavaScript, const is a keyword used to declare a constant variable that cannot be reassigned a new value once it has been initialized. Here's how to use it:

const pi = 3.14;

In this code, pi is a constant variable with the value of 3.14. Once a constant variable has been assigned a value, it cannot be reassigned to a new value:

const pi = 3.14;
pi = 4; // This will result in a TypeError because pi is a constant variable and cannot be reassigned.

Note that const only prevents reassignment of the variable itself, not the value of the object it points to. For example, if you have a const object, you can still modify its properties:

const myObj = { a: 1, b: 2 };
myObj.a = 3; // This is allowed and will change the value of myObj.a to 3.

In addition, const declarations are block-scoped, meaning they can only be accessed within the block they are defined in. For example:

if (true) {
 const x = 1;
 console.log(x); // This will log 1.
}
console.log(x); // This will result in a ReferenceError because x is not defined outside of the if block.

const is often used for values that should not be changed during the execution of a program, such as constants, configuration settings, or library references. By using const, you can ensure that these values remain constant and avoid accidental reassignment.

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• Javascript Const And How To Use It