Your question: What is enum in TypeScript?

What is the use of enum in TypeScript?

Enums are one of the few features TypeScript has which is not a type-level extension of JavaScript. Enums allow a developer to define a set of named constants. Using enums can make it easier to document intent, or create a set of distinct cases. TypeScript provides both numeric and string-based enums.

Should I use enum in TypeScript?

Enums in TypeScript are a very useful addition to the JavaScript language when used properly. They can help make it clear the intent of normally “magic values” (strings or numbers) that may exist in an application and give a type-safe view of them.

What is enum used for?

Enumeration (or enum) is a user defined data type in C. It is mainly used to assign names to integral constants, the names make a program easy to read and maintain. enum State {Working = 1, Failed = 0}; The keyword ‘enum’ is used to declare new enumeration types in C and C++.

When should I use TypeScript enums?

Why use enums in TypeScript?

  1. Provides flexibility making it easier to express and document intentions and use cases.
  2. Saves compile-time and runtime with inline code in JavaScript.
  3. Allows for the creation of memory-efficient custom constants in JavaScript.
  4. Etc.
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Why do we need enum?

Enums are used when we know all possible values at compile time, such as choices on a menu, rounding modes, command line flags, etc. It is not necessary that the set of constants in an enum type stay fixed for all time. In Java (from 1.5), enums are represented using enum data type.

Is enum or constant better?

Enums limit you to the required set of inputs whereas even if you use constant strings you still can use other String not part of your logic. This helps you to not make a mistake, to enter something out of the domain, while entering data and also improves the program readability.

Why is enum bad?

The problem with enums is described in Fowler’s Refactoring, where it is considered a code smell. It has nothing to do with type safety, but rather that it forces you to sprinkle switch statements all over your code, thus violating the DRY Principle.

Is enum a union type?

There’s only one way to use union types, while with enums you can use ButtonStatus. … Enums are compiled to some obscure code, instead of being just removed by the TypeScript compiler. They are one of the few pieces of TS syntax that behave this way.

What is difference between interface and type in TypeScript?

Both the methods Type and the Interface are used to describe the structure of the objects in TypeScript.

Difference between Type and Interface in TypeScript:

Type Interface
It supports the creation of a new name for a type. It provides a way to define the entities.
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What is enum with example?

An enum type is a special data type that enables for a variable to be a set of predefined constants. The variable must be equal to one of the values that have been predefined for it. Common examples include compass directions (values of NORTH, SOUTH, EAST, and WEST) and the days of the week.

Are enums are type-safe?

The enums are type-safe means that an enum has its own namespace, we can’t assign any other value other than specified in enum constants. … Additionally, an enum is a reference type, which means that it behaves more like a class or an interface.

How do you define an enum?

An enum is a special “class” that represents a group of constants (unchangeable variables, like final variables). To create an enum , use the enum keyword (instead of class or interface), and separate the constants with a comma.

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