JavaScript Map.entries() method is used for returning an iterator object which contains all the [key, value] pairs of each element of the map. It returns the [key, value] pairs of all the elements of a map in the order of their insertion. The Map.entries() method does not require any argument to be passed and returns an iterator object of the map.
Syntax:
mapObj.entries()
Parameters:
- It does not require any parameters to be passed.
Return:
- The Map.entries() method returns the [key, value] pairs of all the elements of a map in the order of their insertion.
Examples of the above method are provided below.
Example 1: In this example, a map object “myMap” has been created with three [key, value] pairs, and an iterator object “iterator_obj” method is created which uses Map. entries() method to return the [key, value] pairs of all the elements of a map in the order of their insertion.
javascript
// creating a map objectlet myMap = new Map();// Adding [key, value] pair to the mapmyMap.set(0, 'neveropen');myMap.set(1, 'is an online portal');myMap.set(2, 'for neveropen');// creating an iterator object using Map.entries() methodlet iterator_obj = myMap.entries();// displaying the [key, value] pairs of all the elements of the mapconsole.log(iterator_obj.next().value);console.log(iterator_obj.next().value);console.log(iterator_obj.next().value); |
Output:
Array [0, "neveropen"] Array [1, "is an online portal"] Array [2, "for neveropen"]
Example 2: In this example, a map object “myMap” has been created with three [key, value] pairs, and an iterator object “iterator_obj” method is created which uses Map. entries() method to return the [key, value] pairs of all the elements of a map in the order of their insertion.
javascript
// creating a map objectlet myMap = new Map();// Adding [key, value] pair to the mapmyMap.set(0, 'Maps');myMap.set(1, 'in JavaScript');// creating an iterator object using Map.entries() methodlet iterator_obj = myMap.entries();// displaying the [key, value] pairs of all the elements of the mapconsole.log(iterator_obj.next().value);console.log(iterator_obj.next().value); |
Output:
Array [0, "Maps"] Array [1, "in JavaScript"]
Applications: Whenever we want to get all the [key, value] pairs of each element of a map using an iterator object, we use the Map.entries() method.
Exceptions:
- If the variable is not of the Map type then the Map.entries() operation throws a TypeError.
- If the “iterator_obj.next().value” is used more times as compared to [key, value] pairs of a map, the Map.entries() method returns undefined for all those cases.
To see the difference between the Javascript Map and Objects, go through this Map vs Object In Javascript article.
We have a complete list of Javascript Map methods, to check those please go through this JavaScript Map Complete Reference article.
Supported Browsers:
- Google Chrome 38 and above
- Edge 12 and above
- Firefox 20 and above
- Opera 25 and above
- Safari 8 and above
