Map() is a collection of elements in JavaScript where each element is kept as a Key and value pair. This method applies a callback function as a parameter to each element of the array before returning the updated array.
The Map() keyword is used to generate the object. The map() method loops through each object in the given array. The map() method combines with the entries() method to loop through the object and returns an array containing key-value pairs as its data.
Here we have two methods to iterate Map element in javascript:
- Using for…of loop
- Using forEach loop
Approach 1: Using for…of loop
The for…of loop iterates over the iterable objects (like Array, Map, Set, arguments object, …, etc), invoking a custom iteration hook with statements to be executed for the value of each distinct property.
Syntax:
for ( variable of iterableObjectName) {
...
}
Example: In this example, we are using for…of the loop to iterate over the map object.
Javascript
let newMap = new Map()newMap.set("Cricket", "sport");newMap.set("Apple", "fruit");for (let [key, value] of newMap) { console.log(key + " is " + value);} |
Output:
Cricket is sport
Apple is fruit
Approach 2: Using forEach() loop
The Map.forEach() method is used to loop over the map with the given function and execute the given function over each key-value pair.
Syntax:
myMap.forEach(callback, value, key, thisArg)
Example: Here we show the basic use of the Javascript Map.forEach() method.
Javascript
// Creating a map using Map objectlet newMap = new Map();// Adding values to the mapnewMap.set("Monday", 1);newMap.set("Tuesday", 2);newMap.set("Wednesday", 3);// Logging map object to consolenewMap.forEach((values, keys) => { console.log(values, keys);}); |
1 Monday 2 Tuesday 3 Wednesday
