Type Casting with TypeScript
Type casting is the practice of defining the function or code as best as you can. Below are some basic types that TypeScript checks for:
- string: “TypeScript is awesome!”
- number: 0, 1, 2, etc.
- object: { language: “typescript” }
- boolean:
trueorfalse - undefined: Data is not defined
- void: Nothing
- any: Literary any data type
Let’s annotate our alertMe() function using these types. To annotate an argument or function, you use the colon (:) followed by the type.
functionalertMe(message:string):void{alert(message);}
In this case, we are explicitly defining the message parameter as a string and nothing else. If you compile this function again using the tsc command, this time with the one instance of alertMe(). But this time, pass in a number instead. You will still receive the same error! At this point, TypeScript is no longer inferring the type; this type it’s explicitly stated.
You should have noticed something...