Are There Constants in Javascript?

Are there constants in JavaScript?

JavaScript is a versatile programming language that allows developers to create dynamic and interactive web applications. While JavaScript does not have built-in constants like some other programming languages, there are ways to achieve a similar effect by using certain techniques and best practices.

1. Using the ‘const’ Keyword

The ‘const’ keyword was introduced in ECMAScript 6 (ES6) and allows developers to declare variables that cannot be re-assigned. Although it is not a true constant, it provides a way to enforce immutability in JavaScript.

const PI = 3.14159;
PI = 3.14; // Error: Assignment to constant variable.

2. Object.freeze() Method

The Object.freeze() method can be used to make an object immutable. Once an object is frozen, its properties cannot be added, deleted, or modified.

const person = {
  name: 'John',
  age: 30
};

Object.freeze(person);

person.age = 31; // No effect, as the object is frozen.
console.log(person.age); // Output: 30

3. Uppercase Naming Convention

Another convention followed by JavaScript developers is to use uppercase naming for variables that are intended to be constants. Although this does not enforce immutability, it serves as a visual cue to indicate that the variable should not be modified.

const MAX_WIDTH = 800;

4. Using a Closure

A closure is a function that has access to variables from its outer scope, even after the outer function has finished executing. By creating a closure, you can achieve a form of constant-like behavior in JavaScript.

function createConstant(value) {
  return function() {
    return value;
  };
}

const getPI = createConstant(3.14159);
console.log(getPI()); // Output: 3.14159

While JavaScript does not have true constants, these techniques can help you achieve a similar effect. Whether you choose to use the ‘const’ keyword, Object.freeze(), uppercase naming convention, or closures, it’s important to follow best practices and communicate your intention to other developers working on the codebase.

Are There Constants in Javascript?