คำแทนคำว่า If (เช่น Unless, Provided That, As Long As, In Case) — Bài Tập 1

A function `calculateDiscount(price, coupon)` needs to return 0 if `coupon` is null or invalid. What is the best way to implement this using a guard clause?

What is the result of `const result = (10 > 5) ? 'Greater' : 'Smaller';`?

In a language with optional chaining, if `data` is an array of objects, and you want to safely access the `name` property of the first element, which might not exist, how would you write it?

To provide a default value for a date variable `eventDate` to today's date if it's null or undefined, which operator is most suitable?

A function `fetchData(id)` should return an empty array immediately if `id` is negative. How would you implement this using a guard clause?

Consider the code: `let status = (score > 90) ? 'Excellent' : 'Good';`. What is 'Excellent' if score is 95?

You want to ensure a function parameter `name` always has a value, defaulting to 'Anonymous' if it's not provided or is an empty string. Which operator can help achieve this concisely?

You are building a system that needs to apply different validation rules (e.g., `EmailValidator`, `PasswordValidator`, `AgeValidator`) based on the type of data being validated. Instead of using `if-else if` to select the validator, you store validator instances in a map where keys are data types and values are validator objects. What is this an example of?

You are building a system that needs to retrieve environment variables. If an environment variable is not set, you want to use a default value. Which operator is ideal for this, especially if an empty string is a valid configuration?

When is it generally preferable to use a `switch` statement over a long `if-else if` ladder?