How to Check the Type of a Variable in TypeScript

Check the Type of a Variable in TypeScript

When you “check the type” of a variable in TypeScript, you’re really checking the runtime value and letting the compiler narrow the static type for you. In this tutorial, I’ll walk through the practical ways to do that using typeof, instanceof, and type guards, with examples you can drop into real projects. How to check the type … Read more >>

What does “TypeError: is not a function” mean in TypeScript?

What does “TypeError is not a function” mean in TypeScript

In TypeScript, “TypeError: is not a function” is a runtime JavaScript error that appears when you try to call something with () that is not actually a function. The value might be a string, an object, undefined, null, or some other type that cannot be called. Most of the time, this happens because the variable you are calling does … Read more >>

TypeScript Interface with Functions: 6 Patterns You Need to Know

TypeScript Interface with Functions

TypeScript interfaces can absolutely have functions, and there are several useful patterns beyond the basic “add a method and implement it in a class.” In this tutorial, I’ll walk you through those patterns in a practical, no-nonsense way. Why put functions in a TypeScript interface? When I say “functions in an interface,” I’m really talking … Read more >>

TypeScript Generic Anonymous Functions

TypeScript Generic Anonymous Functions

If you’ve ever copied and pasted the same function logic three times just to handle string, number, and boolean separately, TypeScript generic anonymous functions are the fix. They let you write one flexible, type-safe function expression that adapts to any data type, without losing IntelliSense or compile-time safety. In this tutorial, I’ll walk you through exactly how TypeScript generic … Read more >>

Statistical Learning vs Machine Learning: Which One Should You Actually Use?

Difference Between Statistical Learning and Machine Learning

If you’ve already read five articles on this topic, they probably all said the same thing: “statistical learning focuses on inference, machine learning focuses on prediction.” That’s technically correct, but it doesn’t tell you when to use which, why it matters for your projects, or what the difference looks like in actual Python code. I’ve worked with both … Read more >>

How to Specify Return Type in TypeScript Arrow Functions (With Real‑World Examples)

typescript arrow function return type

TypeScript is very good at guessing (inferring) the return type of your arrow functions, but in real projects, “good enough” inference can still hide bugs. In this tutorial, I’ll walk through how to explicitly specify the return type for arrow functions in TypeScript, and more importantly, when it actually matters. We’ll start with the basics, then move … Read more >>