TypeScript Data Type - Boolean

Boolean values are supported by both JavaScript and TypeScript and stored as true/false values.

TypeScript Boolean:

let isPresent:boolean = true;

Note that, Boolean with an upper case B is different from boolean with a lower case b. Upper case Boolean is an object type whereas lower case boolean is a primitive type. It is always recommended to use boolean, the primitive type in your programs. This is because, while JavaScript coerces an object to its primitive type, the TypeScript type system does not. TypeScript treats it like an object type.

So, instead of writing function checkExistence(b: Boolean) it is recommended to use function checkExistence(b: boolean).