The entries()
method returns a new Array Iterator object containing key/value pairs for each array index.
Example
// defining an array named alphabets
const alphabets = ["A", "B", "C"];
// array iterator object that contains
// key-value pairs for each index in the array
let iterator = alphabets.entries();
// iterating through key-value pairs in the array
for (let entry of iterator) {
console.log(entry);
}
// Output:
// [ 0, 'A' ]
// [ 1, 'B' ]
// [ 2, 'C' ]
entries() Syntax
The syntax of the entries()
method is:
arr.entries()
Here, arr is an array.
entries() Parameters
The entries()
method does not take any parameters.
entries() Return Value
- Returns a new
Array
iterator object.
Note: The entries()
method does not change the original array.
Example 1: Using entries() Method
// defining an array
const languages = ["Java", "C", "C++", "Python"];
// array iterator object that contains
// key-value pairs for each index in the array
let iterator = languages.entries();
// looping through key-value pairs in the array
for (let entry of iterator) {
console.log(entry);
}
Output
[ 0, 'Java' ] [ 1, 'C' ] [ 2, 'C++' ] [ 3, 'Python' ]
In the above example, we have used the entries()
method to get an Array iterator object of the key/value pair of each index in the language array.
We have then looped through iterator that prints the key/value pairs of each index.
Example 2: Using next() Method in Array Iterator Object
Array Iterator object has a built-in method called next()
which is used to get the next value in the object.
Instead of looping through the iterator, we can get the key/value pairs using next().value
. For example:
// defining an array
const symbols = ["#", "$", "*"];
// Array iterator object that holds key/value pairs
let iterator = symbols.entries();
// using built-in next() method in Array iterator object
console.log(iterator.next().value);
console.log(iterator.next().value);
console.log(iterator.next().value);
Output
[ 0, '#' ] [ 1, '$' ] [ 2, '*' ]
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