The “for…in” Loop in JavaScript

The “for…in” loop in JavaScript is used to loop through the properties of an object. It is often used when you want to iterate through the keys of an object and perform some action on each key.

Here’s a simple example of using the “for…in” loop:

    
      <script>
        const person = {
          name: 'John',
          age: 30,
          gender: 'male'
        };

        for (let key in person) {
          console.log(key + ': ' + person[key]);
        }
      </script>
    
  

In this example, we have an object called “person” with three properties: “name”, “age”, and “gender”. We use the “for…in” loop to iterate through the keys of the “person” object and log each key and its corresponding value to the console.

It’s important to note that the “for…in” loop should only be used with objects, as using it with arrays or other types of collections can lead to unexpected results.

Overall, the “for…in” loop is a useful tool for iterating through the properties of an object in JavaScript. It provides a convenient way to perform actions on each key of an object without having to know the exact number of keys beforehand.