Javascript Array - entries() Method

Tutorialsrack 27/08/2022 Jquery Javascript

In this article, you will learn about the javascript Array built-in method Array.prototype.entries().  How does this method work in javascript? 

Array.prototype.entries()

The Array.prototype.entries() method is used to return a new array iterator object that contains the key/value pairs for each index in the given array.

This method does not change the original array.

The Array iterator object has a built-in method called next() which can be used to get the next value from the array iterator object.

Here are some examples of Array.prototype.entries():

const arr = ['Java', 'C#', 'Javascript', 'Python'];

// array iterator object that contains
// key-value pairs for each index in the array
const iterator1 = arr.entries();

console.log(iterator1.next().value);
// expected output: Array [0, "Java"]

console.log(iterator1.next().value);
// expected output: Array [1, "C#"]

//Iterating with index and element
for (const [index, element] of arr.entries()) {
  console.log(index + ":" + element);
}
/*

   Output
------------
"0:Java"
"1:C#"
"2:Javascript"
"3:Python"

*/


// looping through key-value pairs in the array
for (const entry of iterator1) {
  console.log(entry);
}

/*

   Output
------------
[0, "Java"]
[1, "C#"]
[2, "Javascript"]
[3, "Python"]

*/

I hope this article will help you to understand the javascript Array built-in method Array.prototype.entries().

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