What is union type in TypeScript?

What is union type in TypeScript?

TypeScript – Union TypeScript allows us to use more than one data type for a variable or a function parameter. This is called union type. In the above example, variable code is of union type, denoted using (string | number) . So, you can assign a string or a number to it.

What is TypeScript object?

In TypeScript, object is the type of all non-primitive values (primitive values are undefined , null , booleans, numbers, bigints, strings). With this type, we can’t access any properties of a value.

What collections does TypeScript support?

Fundamentally, TypeScript supports two kinds of collections: arrays (where all the members are of the same type and are accessed by position) and tuples (where each member can be of a different type).

How do you use TypeScript?

Setting Up TypeScript

  1. Install the TypeScript compiler. To start off, the TypeScript compiler will need to be installed in order to convert TypeScript files into JavaScript files.
  2. Make sure your editor is setup to support TypeScript.
  3. Create a tsconfig.json file.
  4. Transpile TypeScript to JavaScript.

What are TypeScript types?

Data types in TypeScript

Built-in Data Type keyword Description
Number number It is used to represent both Integer as well as Floating-Point numbers
Boolean boolean Represents true and false
String string It is used to represent a sequence of characters
Void void Generally used on function return-types

How do you type two TypeScript?

TypeScript allows you to define multiple types. The terminology for this is union types and it allows you to define a variable as a string, or a number, or an array, or an object, etc. We can create union types by using the pipe symbol ( | ) between each type.

What is export type in TypeScript?

TypeScript supports export = to model the traditional CommonJS and AMD workflow. The export = syntax specifies a single object that is exported from the module. This can be a class, interface, namespace, function, or enum.

What are the different types in TypeScript?

How do you check TypeScript type?

TypeScript have a way of validating the type of a variable in runtime. You can add a validating function that returns a type predicate. So you can call this function inside an if statement, and be sure that all the code inside that block is safe to use as the type you think it is.

Can you use TypeScript with HTML?

A JavaScript library has already been developed for this purpose – it’s called TypeScript Compile, and it allows typescript to be embedded in HTML (as shown above.)

How do you type TypeScript types?


  1. Use PascalCase for type names.
  2. Do not use I as a prefix for interface names.
  3. Use PascalCase for enum values.
  4. Use camelCase for function names.
  5. Use camelCase for property names and local variables.
  6. Use _ as a prefix for private properties.
  7. Use whole words in names when possible.

How do I create a union in TypeScript?

To convert an array of strings into a string literal union type in TypeScript, you can first define the array of strings then make the array as readonly using the as const keyword, and then use the typeof operator on all the values contained in the array.

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