In TypeScript, we can return a value from a method or function using the return statement followed by the value we want to return. Here's an example of a method that returns a string value:
function greet(name: string): string {
return Hello, ${name}!;
}
const message: string = greet("John");
console.log(message); // Output: Hello, John!
In the above example, the greet function takes a string parameter name and returns a string value which is a greeting message. The return statement returns the message with the provided name using a string interpolation.
We can also return other primitive data types like number, boolean, or even undefined:
function double(value: number): number {
return value * 2;
}
const num: number = double(5); // Returns 10
console.log(num); // Output: 10
function isValidEmail(email: string): boolean {
return /^[\w-.]+@([\w-]+\.)+[\w-]{2,4}$/.test(email);
}
const email: string = "example@test.com";
const isValid: boolean = isValidEmail(email); // Returns true
console.log(isValid); // Output: true
function doSomething(): undefined {
// some logic here
return undefined; // return type is undefined
}
In the above examples, we can see that we can return a value of same data type as that of the return type specified in the method/function signature. Additionally, we can also return undefined if there is no value to be returned.