Instruction: Explain the concept of Type Guards and how they are used with an example.
Context: This question tests the candidate's knowledge of Type Guards and their ability to utilize them to influence the type checking behavior of TypeScript.
Official answer available
Preview the opening of the answer, then unlock the full walkthrough.
Imagine we have a function that takes an input parameter that could either be a number or a string. Our objective is to process this input differently based on its type. Without Type Guards, we'd be limited in our ability to leverage TypeScript's type system for more precise operations. Here's where Type Guards come into play. By using Type Guards, we can perform a runtime check to determine the type of the input and then narrow down its type within the conditional block.
typescript function processInput(input: number | string) { if (typeof input === "string") { // Within this block, `input` is treated as a string console.log(input.toUpperCase()); // This is safe...
easy
easy
medium
medium
medium
hard