Working with String Literal Types in TypeScript

Working with String Literal Types in TypeScript

String literal types are a great way to ensure that you only assign certain strings to variables in your TypeScript code. By restricting strings to specific values, you can avoid common errors like typos and case sensitivity.

String literal types are similar to string enum types except they can only be a single value. In other words, a string literal type cannot have multiple values. For example, a string literal type might be used to restrict the value of a variable to either "red" or "blue".

To create a string literal type in TypeScript, you must use the type keyword followed by an identifier and then the values enclosed in single quotation marks.

type color = 'red' | 'blue';

let myColor: color = 'red';

In this example, the color type has been created and it is restricted to two values - red and blue. A variable called myColor has also been created and it is of the color type. As a result, the only value that can be assigned to myColor is either "red" or "blue". Any other value will cause a compilation error.

String literal types allow you to quickly and easily add an extra layer of safety to your code so that users can only assign valid strings to variables. Combined with the power of TypeScript's type system, string literal types are invaluable for catching errors and ensuring code quality.