คำแทนคำว่า If (เช่น Unless, Provided That, As Long As, In Case) — Bài Tập 2

Which of the following is NOT a keyword typically associated with a `switch` statement?

In JavaScript, if you have `const user = null; const username = user?.name ?? 'Guest';`, what will `username` be?

A function `processInput(data)` should immediately stop and return an error if `data` is null. Which alternative to `if-else` is best for this?

To manage different actions based on user input (e.g., 'add', 'edit', 'delete'), you store functions in a dictionary/map where keys are the input strings and values are the corresponding functions. What is this technique called?

Which operator provides a concise way to write conditional expressions, often replacing simple if-else statements?

To provide a default empty object for a variable `options` if it's null or undefined, which operator is most suitable?

You are building a system that needs to retrieve configuration values (e.g., `API_KEY`, `DATABASE_URL`) from 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?

You are building a GUI application where various menu items (e.g., 'Save', 'Open', 'Copy') need to perform different actions when clicked. Instead of using a large `if-else if` block to check which item was clicked and then execute its logic, you encapsulate each action into a separate object. Which design pattern does this describe?

Which of the following is a common use case for the ternary operator?

You want to log a message only if a `debugMode` flag is true. Which short-circuiting operator can achieve this concisely?