Maps

In TypeScript, a map is a collection of key-value pairs that can be used to store and retrieve data. Maps are similar to arrays, but instead of using a numeric index to access values, maps use keys to access values.

In TypeScript, maps can be implemented using the built-in Map type. Here’s an example of how to define and use a map in TypeScript:

const myMap = new Map<string, number>();

myMap.set("foo", 1);
myMap.set("bar", 2);


console.log(myMap.get("foo"));

console.log(myMap.has("baz"));

console.log(myMap.delete("foo"));

for (const [key, value] of myMap.entries()) {
  console.log(`${key}: ${value}`);
}

In the above example, we define a map with string keys and number values using the Map<string, number> syntax. We then add key-value pairs to the map using the set method, and retrieve a value from the map using the get method. We also check if a key exists in the map using the has method, remove a key-value pair from the myMap.

Example #

// Define the type for the keys and values of the map
type MyKeyType = string;
type MyValueType = number;

// Define the map using the types for keys and values
const myMap: Map<MyKeyType, MyValueType> = new Map();

// Add entries to the map
myMap.set("one", 1);
myMap.set("two", 2);
myMap.set("three", 3);

// Access the values in the map
console.log(myMap.get("one"));
console.log(myMap.get("two"));
console.log(myMap.get("three"));

// Loop through the entries in the map
for (const [key, value] of myMap.entries()) {
  console.log(`${key}: ${value}`);
}

In this example, MyKeyType is a type alias for the key type of the map, which is string. MyValueType is a type alias for the value type of the map, which is number.

You can also use other types for the keys and values of the map, depending on your needs.