JavaScript for in

In JavaScript, you can cycle through an object's attributes by using the for...in the loop iteration type.

The basic syntax is as follows:

for (variable in object) { // code to be executed }

In this syntax, the variable is a variable that will hold the property name for each iteration, and the object is the object you want to iterate over.

This is an example:

let person = { firstName: "Olise", lastName: "Eke", age: 30 }; 
for (let property in person) { console.log(property + ": " + person[property]); }

In this example, you will create an object called a person with three properties: firstName, lastName, and age. you will then use a for...in the loop to iterate over the properties of the person object and log their names and values to the console.

The output of this code will be:

firstName: Olise lastName: Eke age: 30

Note that the for...in loop iterates over all properties of an object, including its inherited properties. If you only want to iterate over the object's properties, you can use the hasOwnProperty() method to check if each property is a direct property of the object,

Example:

for (let property in person) { if (person.hasOwnProperty(property)) 
{ console.log(property + ": " + person[property]); } }

This will only log the object's properties to the console, excluding any inherited properties.