Learn React with TypeScript 3

--noImplicitReturns

This ensures we return a value in all branches of a function if the return type isn't void.

Let's see this in action with an example:

1. In our OrderDetail class, let's say we have the following implementation for our getTotal method:

getTotal(discount: number): number {  if (discount) {    const priceWithoutDiscount = this.product.unitPrice * this.quantity;    const discountAmount = priceWithoutDiscount * discount;    return priceWithoutDiscount - discountAmount;  } else {    // We forgot about this branch!  }}

2. We've forgotten to implement the branch of code that deals with the case where there is no discount. If we compile the code without the --noImplicitReturns flag, it compiles fine:

tsc orderDetail

3. However, let's see what happens ...