Map and Set

Map<K, V> compiles to HashMap<K, V>. Set<T> compiles to HashSet<T>.

Map

Creating a Map

const scores: Map<string, i32> = new Map();

With initial entries:

const config: Map<string, string> = new Map([
  ["host", "localhost"],
  ["port", "8080"],
]);

Setting and getting

const map: Map<string, i32> = new Map();

map.set("alice", 100);
map.set("bob", 85);

const score = map.get("alice");   // 100

Checking and deleting

map.has("alice");      // true
map.delete("alice");   // removes the entry
map.clear();           // removes all entries

Size

const count = map.size;   // number of entries

Iterating

const map: Map<string, i32> = new Map();
map.set("a", 1);
map.set("b", 2);

// Keys
for (const key of map.keys()) {
  console.log(key);
}

// Values
for (const val of map.values()) {
  console.log(`${val}`);
}

// Entries
for (const entry of map.entries()) {
  console.log(`${entry}`);
}

// forEach
map.forEach((value: i32, key: string) => {
  console.log(`${key}: ${value}`);
});

Map methods reference

| Method | Rust equivalent | |--------|----------------| | .get(key) | .get(key).cloned() | | .set(key, value) | .insert(key, value) | | .has(key) | .contains_key(key) | | .delete(key) | .remove(key) | | .clear() | .clear() | | .keys() | .keys() | | .values() | .values() | | .entries() | .iter() | | .forEach(fn) | .iter().for_each(fn) | | .size | .len() as i64 |

Set

Creating a Set

const tags: Set<string> = new Set();

From an iterable:

const unique: Set<i32> = new Set([1, 2, 3, 2, 1]);  // {1, 2, 3}

Adding and checking

const set: Set<string> = new Set();

set.add("rust");
set.add("typescript");

set.has("rust");      // true
set.has("python");    // false

Removing

set.delete("rust");   // removes "rust"
set.clear();          // removes all elements

Size

const count = set.size;

Iterating

const set: Set<string> = new Set();
set.add("a");
set.add("b");

for (const item of set.values()) {
  console.log(item);
}

set.forEach(item => console.log(item));

Set methods reference

| Method | Rust equivalent | |--------|----------------| | .add(value) | .insert(value) | | .has(value) | .contains(value) | | .delete(value) | .remove(value) | | .clear() | .clear() | | .keys() | .iter() | | .values() | .iter() | | .entries() | .iter() | | .forEach(fn) | .iter().for_each(fn) | | .size | .len() as i64 |