How To Check If A Variable Is An Es6 Class Declaration

Are you working on JavaScript projects and wondering how you can check if a variable is an ES6 class declaration? Determining the type of variable in JavaScript, especially when dealing with ES6 class declarations, can be a handy skill to have in your coding toolkit. In this article, we'll guide you through the steps to check if a variable is an ES6 class declaration in JavaScript.

To accomplish this task, you can use the combination of the `typeof` and `class` keywords. When a variable holds an ES6 class declaration, the `typeof` operator will return "function" because classes in JavaScript are essentially functions.

Here's a practical example to help you understand the process better:

class Car {
  constructor(brand) {
    this.brand = brand;
  }
}

const myCar = new Car('Toyota');

console.log(typeof Car); // Output: function
console.log(typeof myCar); // Output: object
console.log(myCar instanceof Car); // Output: true

In the code snippet above, we define an ES6 class `Car` that represents a car object. When we use the `typeof` operator on the `Car` class, it returns "function". This indicates that `Car` is a function, which aligns with how ES6 classes are implemented in JavaScript.

Additionally, by creating an instance of the `Car` class with `new Car('Toyota')`, we can check if the `myCar` variable is an instance of the `Car` class using the `instanceof` operator. In this case, the output will be `true`, confirming that `myCar` is an instance of the `Car` class.

It's important to note that when using the `typeof` operator with an instance of an ES6 class (such as `myCar`), it will return "object". This is expected behavior because instances of classes in JavaScript are objects.

If you need to check whether a given variable is an ES6 class declaration at runtime, you can follow these steps:

1. Use the `typeof` operator with the variable in question.
2. Verify that the result is "function", indicating a class declaration.
3. If needed, use the `instanceof` operator to confirm that the variable is an instance of the specific class.

By following these steps and understanding how JavaScript handles ES6 class declarations, you can effectively check if a variable is an ES6 class declaration in your projects. This knowledge can be helpful when working with complex codebases or debugging scenarios where variable types need to be identified dynamically.