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JavaScript - Map.get() Method

In JavaScript, the Map.get() method is used to return the "value" associated with the specified key. It takes 'key' as a parameter; if the provided key exists in the Map object, this method returns the corresponding value. If the key is found in the Map object, it returns 'undefined' as result.

If the value associated with a key in a Map is an object, then Map.get() returns a reference to that object. Consequently, any changes made to that object will be reflected inside the Map object as well.

This method is compatible on almost every browser such as Chrome, Edge, Firefox, Opera, and Safari.

Syntax

Following is the syntax of JavaScript Map.get() method −

get(key)

Parameters

This method accepts only one parameter. The same is described below −

  • key − The key whose associated "value" is to be retrieved from the map.

Return value

This method returns the "value" associated with the specified key, or it returned "undefined" if the key does not exist in the Map object.

Examples

Example 1

The following example demonstrates the basic usage of JavaScript Map.get() method −

<html>
<body>
   <script>
      let map = new Map();
      map.set(1, 'apple');
      map.set(2, 'banana');
      map.set(3, 'cherry');
      
      document.write(map.get(2));
   </script>
</body>
</html>

If we execute the above program, it returns the value ("banana") associated with the specified key "2".

Example 2

If the provided key does not exist in the Map object, this method returns "undefined" as result.

Here, we are retrieving the associated value of the key ("4") in the Map object −

<html>
<body>
   <script>
      let map = new Map();
      map.set(1, 'apple');
      map.set(2, 'banana');
      map.set(3, 'cherry');
      document.write(map.get(4));
   </script>
</body>
</html>

After executing the above program, it returns "undefined" as result.

Example 3

If the do not pass any argument to the get() method, it returns "undefined" as result.

<html>
<body>
   <script>
      let map = new Map();
      map.set(1, 'apple');
      map.set(2, 'banana');
      map.set(3, 'cherry');
      
      document.write(map.get());
   </script>
</body>
</html>

After executing the above program, it returns "undefined" as result.

Example 4

In this example, we first created an object "obj" with a 'name' and 'age' properties and added it to the Map using the key '1'. Then, we retrieved the object from the Map using Map.get() and store it in "retrievedObj". We then modified retrievedObj by updating the age property.

Finally, when we retrieve the object associated with '1' again using Map.get(), we see that the changes made to retrievedObj have been reflected in the original object stored in the Map.

<html>
<body>
   <script>
      const map = new Map();
      
      // Create an object and add it to the Map
      const obj = { name: 'Varun', age: 45 };
      map.set('1', obj);
   
      // Retrieve the object from the Map
      const retrievedObj = map.get('1');
   
      // Modify the retrieved object
      retrievedObj.age = 55;
   
      document.write(JSON.stringify(map.get('1'))); // Output: { name: 'Varun', age: 55 }
   </script>
</body>
</html>

As we can see in the output, the changes has been reflected in the original Map object.

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