TypeScript Lowercase<StringType> Template Literal Type

In this article, we are going to learn about the Lowercase<StringType> Template Literal Type in TypeScript. TypeScript is a popular programming language used for building scalable and robust applications. One of its features is the Lowercase<StringType> Template Literal Type, a built-in utility type that aids in string manipulation. It converts each character in a string to its lowercase version.

Syntax:

type LowercaeString= Lowercase<Stringtype>

Where-

• Lowercase is the utility itself.
• StringType is the type you want to convert to lowercase. This is the input type that you want to convert to lowercase. It can be a string literal type, a string union type, or any other string type.

Example 1: In this example, we will see a simple example of using Lowercase<StringType> Template Literal. 'MyString' is defined as "HelloWorld" and LowercaseString is defined as 'Lowercase<MyString>. The result is that 'LowercaseString' will be of type "helloworld", with all characters in lowercase.

type MyString = "HelloWorld"
type LowercaseString = Lowercase<MyString> 
const result: LowercaseString = "helloworld"
console.log(result)

Output:

helloworld

Example 2: In this example, we have a 'Course' type that can only take on three specific string values: "Java", "python", and "React". We then use the 'Lowercase' template literal type to create 'LowercaseCourse' which ensures that any value assigned to it must be lowercase. React will give an error since it is not in lower. Others are in lowercase so they will not cause errors.

type Course = "Java" | "Python" | "React"; 
type LowercaseCourse = Lowercase<Course>; 
const myCourse: LowercaseCourse = "java" // Valid 
const myCourse2: LowercaseCourse = "python" // Valid 
// const myCourse3:LowercaseCourse="React" // Invalid 
console.log(myCourse) 
console.log(myCourse2)

Output:

java python

21mcsrltd

Follow

Improve

Article Tags :

• JavaScript
• Web Technologies
• Geeks Premier League
• TypeScript
• Geeks Premier League 2023

+1 More