In JavaScript, a Map is a built-in object that allows us to store key-value pairs, where both the keys and the values can be of any type.
This makes maps a versatile data structure for associating information.
Here's a basic overview of how we can use Map in JavaScript:
// Creating an empty Map
let yourMap = new Map();
// Adding entries to a Map
yourMap.set('name', 'Alice');
yourMap.set('age', 23);
// Creating a Map with initial key-value pairs
let keyValueMap = new Map([
['key1', 'value1'],
['key2', 'value2'],
['key3', 'value3']
]);
// Printing yourMap Object
// Output: Map(2) { 'name' => 'Alice', 'age' => 23 }
console.log(yourMap)
// Output: { 'key1' => 'value1', 'key2' => 'value2', 'key3' => 'value3' }
console.log(keyValueMap)
set(key, value): Adds a new key-value pair to the Map.
let yourMap = new Map();
// Adding entries to a Map
yourMap.set('name', 'Alice');
yourMap.set('age', 23);
// set method
yourMap.set('gender', 'female');
let yourMap = new Map();
yourMap.set('name', 'Alice');
yourMap.set('age', 23);
yourMap.set('gender', 'female');
// get method for retrieving value associated with specified key
console.log(yourMap.get('name')); // 'Alice'
let yourMap = new Map();
yourMap.set('name', 'Alice');
yourMap.set('age', 23);
yourMap.set('gender', 'female');
// check `key` exists in `map` object
console.log(yourMap.has('gender')); // true
console.log(yourMap.has('profession')); // false
let yourMap = new Map();
yourMap.set('name', 'Alice');
yourMap.set('age', 23);
yourMap.set('gender', 'female');
// remove key from map object
yourMap.delete('age');
let yourMap = new Map();
yourMap.set('name', 'Alice');
yourMap.set('age', 23);
yourMap.set('gender', 'female');
yourMap.delete('age');
console.log(yourMap.size);
// Output: 2 -> now, yourMap contains :-> name and gender, age we have deleted.
let yourMap = new Map();
yourMap.set('name', 'Alice');
yourMap.set('age', 23);
yourMap.set('gender', 'female');
yourMap.delete('age');
yourMap.clear();
get(key): Retrieves the value associated with the specified key.
has(key): Returns a boolean indicating whether the Map contains a specific key.
yourMap.forEach((value, key) => {
console.log(key, value);
});
// Or using a for...of loop
for (let [key, value] of yourMap) {
console.log(key, value);
}
delete(key): Removes the entry with the specified key from the Map.
size: Returns the number of entries (key-value pairs) in the Map.
clear(): Removes all entries from the Map.
We can use the forEach method or the for...of loop to iterate over the entries of a Map.
Map is particularly useful when we need to associate unique keys with values, and it provides more flexibility compared to using objects as keys in plain JavaScript objects.