Explain the use of the readonly modifier in TypeScript ?

The readonly modifier in TypeScript is used to define the class properties or the variables whose values can not be modified again once they are assigned with a value initially. It is a way of expressing the immutability of the code by defining the properties with immutable values and making the code more robust by preventing unintentional changes in the code. You can define the readonly class properties using the readonly keyword, while the const keyword to define the readonly variables. The below syntax shows how you can define readonly properties and variables in TypeScript.

Syntax:

class class_name{
    readonly property_name: type = value;
}

const variable_name: type = value;