TypeScript Map

TypeScript Map is a collection that stores key-value pairs, where keys can be of any type. It maintains the insertion order of keys and provides methods to add, retrieve, check, remove, and clear entries, ensuring efficient management of key-value data.

Creating a Map

A map can be created as:

let myMap = new Map();

Map Methods

Iterating Map Data

Iterating over the key-value pairs in a TypeScript Map can be done using various methods. The forEach the method is commonly used for this purpose.

Example 1: Using the forEach Method

In this example, we are using the forEach method to Iterate over map data:

let myMap = new Map<string, number>();
myMap.set('one', 1);
myMap.set('two', 2);
myMap.set('three', 3);

myMap.forEach((value, key) => {
  console.log(`Key: ${key}, Value: ${value}`);
});

Output:

Key: one, Value: 1
Key: two, Value: 2
Key: three, Value: 3

Example 2: Common Operations on a TypeScript Map

In this example, KeyType is string, and ValueType is number. The methods demonstrate common operations on a TypeScript Map.

let myMap = new Map<string, number>();
myMap.set('one', 1);
myMap.set('two', 2);

console.log(myMap.get('one')); // Output: 1
console.log(myMap.has('two')); // Output: true

myMap.delete('two');
console.log(myMap.get('two')); // Output: undefined

console.log(`Size: ${myMap.size}`); // Output: Size: 1

myMap.clear();
console.log(`Size after clear: ${myMap.size}`); // Output: Size after clear: 0

myMap.set('one', 1);
myMap.forEach((value, key) => {
  console.log(`Key: ${key}, Value: ${value}`);
});

Output:

1
true
undefined
Size: 1
Size after clear: 0
Key: one, Value: 1