Data types in TypeScript
Last Updated :
21 Jan, 2025
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In TypeScript, a data type defines the kind of values a variable can hold, ensuring type safety and enhancing code clarity.
- Primitive Types: Basic types like number, string, boolean, null, undefined, and symbol.
- Object Types: Complex structures including arrays, classes, interfaces, and functions.
Primitive Types
Primitive types are the most basic data types in TypeScript. They represent simple, immutable values and are directly assigned.
| Type | Keyword | Description |
|---|---|---|
| Number | number | Represents both integer and floating-point numbers. |
| String | string | Represents textual data. |
| Boolean | boolean | Represents logical values: true or false. |
| Null | null | Represents the intentional absence of any object value. |
| Undefined | undefined | Represents an uninitialized variable. |
| Symbol | symbol | Represents a unique, immutable value, often used as object keys. |
| BigInt | bigint | Represents integers with arbitrary precision. |
Object Types
Object types are more complex structures that can contain multiple values and functions. They are mutable and can be manipulated after creation.
| Type | Description |
|---|---|
| Object | Represents any non-primitive type; however, its use is discouraged in favor of more specific types. |
| Array | Represents a collection of elements of a specific type. |
| Tuple | Represents an array with a fixed number of elements of specific types. |
| Enum | Represents a set of named constants, allowing for a collection of related values. |
| Function | Represents a callable entity; can define parameter and return types. |
| Class | Defines a blueprint for creating objects with specific properties and methods. |
| Interface | Describes the shape of an object, specifying property names and types. |
Advanced Types
TypeScript also offers advanced types that provide additional capabilities for complex type definitions:
| Type | Description |
|---|---|
| Union Types | Allows a variable to hold one of several types, providing flexibility in type assignments. |
| Intersection Types | Combines multiple types into one, requiring a value to satisfy all included types. |
| Literal Types | Enables exact value types, allowing variables to be assigned specific values only. |
| Mapped Types | Creates new types by transforming properties of an existing type according to a specified rule. |
Best Practices of Using Data types in TypeScript
- Use let and const Instead of var: Prefer let and const for block-scoped variables to avoid issues with hoisting and scope leakage.
- Avoid the any Type: Refrain from using any as it bypasses type checking; opt for specific types to maintain type safety.
- Leverage Type Inference: Allow TypeScript to infer types when possible, reducing redundancy and enhancing code readability.
- Utilize Utility Types: Employ built-in utility types like Partial<T> and Readonly<T> to create flexible and readable type definitions.
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