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JavaScript hashmap

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JavaScript does not have a built-in hashmap data structure, but you can implement one using objects. In JavaScript, objects can be used as maps, where you can store key-value pairs.

The syntax for creating an object in JavaScript.

Here, we declare a constant variable myMap and assign an empty object to it using curly braces {}.

const myMap = {};

To add key-value pairs to the map use the bracket notation:

myMap['key'] = 'value';

Access the value associated with a key in the map using the bracket notation.

const value = myMap['key'];

Check if a key exists in the map using the in operator as follows:

if ('key' in myMap) {
  // do something
}

Remove a key-value pair from the map using the delete operator:

JavaScript hashmap example

Simple example code While JavaScript doesn’t have a built-in hashmap data structure, you can implement one using objects.

<!DOCTYPE html>
<html>
<body>
    <script>
       const myMap = {};

        // Adding key-value pairs to the map
        myMap['apple'] = 2;
        myMap['banana'] = 3;
        myMap['orange'] = 5;

        // Accessing values using keys
        console.log(myMap['apple']); // output: 2

        // Checking if a key exists in the map
        if ('apple' in myMap) {
            console.log('apple exists in the map');
        } else {
            console.log('apple does not exist in the map');
        }

        // Removing a key-value pair from the map
        delete myMap['banana'];

        // Iterating over key-value pairs in the map
        for (const key in myMap) {
            console.log(`${key}: ${myMap[key]}`);
        }

    </script>
</body>
</html>

Output:

JavaScript hashmap

Do comment if you have any doubts or suggestions on this Js Hashmap topic.

Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.

OS: Windows 10

Code: HTML 5 Version

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