Enums in TypeScript: Unleashing Their Advantages over Plain JavaScript Objects

Introduction:

Enums, short for enumerations, are a powerful feature offered by TypeScript, a superset of JavaScript. Enums provide developers with a way to define a set of named constant values, making the code more readable, maintainable, and less error-prone. So, In this blog, we’ll delve into the concept of enums, explore their advantages over plain JavaScript objects, and provide illustrative examples to showcase their usage.

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Understanding Enums:

Enums in TypeScript allow you to define a collection of related constant values that can be assigned to a variable. This ensures that the variable’s value is limited to a predefined set of options, making the code more descriptive and self-explanatory.

Advantages of Enums over Plain JavaScript Objects:

Readability and Self-Documentation:

Enumerations enhance code readability by providing meaningful names to constant values. This reduces the need for comments or additional documentation to explain the purpose of each value.

Therefore, Let’s consider the following comparison:

// Using Enums
enum Days {
  Sunday,
  Monday,
  Tuesday,
  Wednesday,
  Thursday,
  Friday,
  Saturday,
}

const today = Days.Wednesday;

// Using Plain JavaScript Objects
const days = {
  Sunday: 0,
  Monday: 1,
  Tuesday: 2,
  Wednesday: 3,
  Thursday: 4,
  Friday: 5,
  Saturday: 6,
};

const today = days.Wednesday;

Therefore, Enumerations provide a cleaner and more intuitive way to work with named values.

Type Safety:

Enumerations provide type safety by ensuring that the value assigned to an enum variable is one of the predefined constants. So, this prevents accidental assignments of incorrect values.

enum Colors {
  Red,
  Green,
  Blue,
}

const selectedColor: Colors = Colors.Green; // Valid
const selectedColor: Colors = "Yellow";    // Error: Type '"Yellow"' is not assignable to type 'Colors'

With plain JavaScript objects, type safety is not guaranteed, and it’s possible to assign arbitrary values to properties.

Auto-Numbering:

Enums automatically assign numeric values to each constant, starting from 0 by default. This can be advantageous when dealing with situations where sequential numbering is required.

enum Status {
  Pending,   // 0
  Approved,  // 1
  Rejected,  // 2
}

Reverse Mapping:

Enumerations offer reverse mapping, allowing you to obtain the constant name from its value.

enum Fruit {
  Apple,
  Banana,
  Cherry,
}

const selectedFruit = Fruit.Banana;
const fruitName = Fruit[selectedFruit]; // "Banana"

Therefore, achieving reverse mapping with plain JavaScript objects requires additional manual effort.

Intellisense and IDE Support:

Enums provide better intelligence and support in modern Integrated Development Environments (IDEs). This aids developers by suggesting available enum values and facilitating code completion.

Conclusion:

Enums in TypeScript bring several advantages over plain JavaScript objects, including enhanced readability, type safety, auto-numbering, reverse mapping, and improved IDE support. Thus, they provide a structured and meaningful way to define sets of related constant values, making code more maintainable, self-documenting, and less prone to errors. So, by leveraging the power of enums, developers can create more robust and organized codebases, leading to improved code quality and development efficiency.

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