The Map
constructor in JavaScript allows you to create a collection of key-value pairs, where each key is unique. Here’s how you can use the Map
constructor:
const map = new Map();
You can also initialize the map with an array of key-value pairs:
const map = new Map([
['key1', 'value1'],
['key2', 'value2'],
...
]);
Once you have created a Map
object, you can add, retrieve, and remove key-value pairs using the following methods:
set(key, value)
: Adds a new key-value pair to the map.get(key)
: Returns the value associated with the given key.has(key)
: Returns a boolean indicating whether the map has a key-value pair with the given key.delete(key)
: Removes the key-value pair with the given key.clear()
: Removes all key-value pairs from the map.
Here’s an example that demonstrates how to use these methods:
const map = new Map();
// Adding key-value pairs
map.set('key1', 'value1');
map.set('key2', 'value2');
// Retrieving values
console.log(map.get('key1')); // Output: value1
// Checking for keys
console.log(map.has('key1')); // Output: true
// Removing key-value pairs
map.delete('key1');
console.log(map.has('key1')); // Output: false
// Clearing the map
map.clear();
console.log(map.size); // Output: 0
Note that the Map
constructor also has a size
property that returns the number of key-value pairs in the map.
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