Ads by ProfitSence

Close

For in Loop JavaScript Code Example

Last Updated on Wednesday 5th Oct 2022

for in loop iterates through all the properties of a particular object.
It is Special loop beacuse you can pair it up with array.

			
					for (let variable in obj) {
    // do some stuff here
}

It will loop through the properties of an array just like it did with the properties of an object.
The for-in loops provide us the most straightforward way to loop over object keys and values.

Example 1

			
					let Captains = {
    "England": "Harry Kane",
    "Italy": "Giorgio Chiellini",
    "Germany": "Manuel Neuer"
}

for (let name in Captains) {
    console.log(name, ':', Captains[name]);
}

In this Example , the for in loop tends to iterate the object.
With Each Iteration it returns the key and uses the key to access the specific value of that key that is object Captains.

			
					// England : Harry Kane
// Italy : Giorgio Chiellini
// Germany : Manuel Neuer

Example 2

			
					let books = ["Fist of the North Star", "Tokyo Ghoul", "Berserk"]

for (let book in books) {
    console.log(book, ":", books[book]);
}

			
					// 0 : Fist of the North Star
// 1 : Tokyo Ghoul
// 2 : Berserk

Example 3

			
					let a = [];

let array = ['a', 'b', 'c', 'd'];

for (let index in array) {
    a += array[index];
}

console.log(a) // abcd

When using with arrays, the order of is independent of implementation.
You Cannot access the values of the array in order that you except.