Map<K, V> class

NOTE: For 2.0 the #constructor arguments have changed. Map now optionally accepts a collection, and only checks types in TypeScript.

An unordered iterable collection of key/value pairs that cannot contain two instances of the same key. In TypeScript it is a generic class that enforces at compile-time the type of the key and the type of the associated value.

To create a Map:

  var map = new go.Map(); // In TypeScript: new go.Map<string, number>();
  map.add("one", 1);
  map.add("two", 2);
  map.add("three", 3);
  // now map.count === 3
  // and map.getValue("two") === 2
  // and map.contains("zero") === false

You can iterate over the key/value pairs in a Map:

  var it = aMap.iterator;
  while (it.next()) {
    console.log(it.key + ": " + it.value);
  }

Or:

  aMap.each(kvp => {
    console.log(kvp.key + ": " + kvp.value);
  });

But note that there is no guaranteed ordering amongst the key/value pairs.

Call #toKeySet to get a read-only Set that holds all of the keys of a Map. Iterating over that Set will produce values that are the keys in the Map.

Although not precisely implementing the features and semantics of the EcmaScript 6 Map class, this GoJS Map class has synonyms for the following methods and property:

• get(key): #getValue, but returns null instead of undefined when key is not present
• set(key,val): #add
• has(key): #contains
• delete(key): #remove
• clear(): #clear
• size: #count

The constructor now takes an optional Iterable or Array argument that provides the initial entries for the new Map.

Note that GoJS iteration is quite different than ES6 iteration, so that functionality has not been made somewhat compatible. These collection classes were defined in GoJS before the ES6 collection classes were proposed.

Available extensions

• Map$Typings

Annotations

• @JS()
• @staticInterop

Constructors

Map([Object? coll])

factory

Properties

count ↔ num

Available on Map<K, V>, provided by the Map$Typings extension

This read-only property is the number of associations in the Map.

getter/setter pair

hashCode → int

The hash code for this object.

no setter, inherited

iterator ↔ IMapIterator<K, V>

Available on Map<K, V>, provided by the Map$Typings extension

Gets an object that you can use for iterating over the key-value pairs of a Map. Typical usage:

getter/setter pair

iteratorKeys ↔ Iterator<K>

Available on Map<K, V>, provided by the Map$Typings extension

Gets an object that you can use for iterating over the keys of a Map. Typical usage:

getter/setter pair

iteratorValues ↔ Iterator<V>

Available on Map<K, V>, provided by the Map$Typings extension

Gets an object that you can use for iterating over the values of a Map. Typical usage:

getter/setter pair

runtimeType → Type

A representation of the runtime type of the object.

no setter, inherited

size ↔ num

Available on Map<K, V>, provided by the Map$Typings extension

This read-only property is the number of associations in the Map.

getter/setter pair

Methods

add(K key, V val) → Map<K, V>

Available on Map<K, V>, provided by the Map$Typings extension

Adds a key-value association to the Map, or replaces the value associated with the key if the key was already present in the map.

addAll(Object coll) → Map<K, V>

Available on Map<K, V>, provided by the Map$Typings extension

Adds all of the key-value pairs of another Map to this Map. If a key is already present in this Map, its value is replaced with the corresponding value from the given map.

all(bool pred(KeyValuePair<K, V>)) → bool

Available on Map<K, V>, provided by the Map$Typings extension

This is true if all invocations of the given predicate on items in the collection are true.

any(bool pred(KeyValuePair<K, V>)) → bool

Available on Map<K, V>, provided by the Map$Typings extension

This is true if any invocation of the given predicate on items in the collection is true.

clear() → void

Available on Map<K, V>, provided by the Map$Typings extension

Clears the Map, removing all key-value associations. This sets the #count to zero.

contains(K key) → bool

Available on Map<K, V>, provided by the Map$Typings extension

Returns whether the given key is in this Map. @param {K} key The key to look up in the Map. @return {boolean} Whether or not the key is contained within the Map.

copy() → Map<K, V>

Available on Map<K, V>, provided by the Map$Typings extension

Makes a shallow copy of this Map. The keys and their values are not copied, so if they are objects they may continue to be shared with the original Map. @expose @return {Map.<K,V>} The new Map with copies of the same entries.

delete(K key) → bool

Available on Map<K, V>, provided by the Map$Typings extension

Removes a key (if found) from the Map.

each(void func(KeyValuePair<K, V>)) → Map<K, V>

Available on Map<K, V>, provided by the Map$Typings extension

Call the given function on each key/value pair in the collection. @expose @param {function(KeyValuePair.<K,V>)} func The argument to the function will be an object with both "key" and "value" properties. This function must not modify the collection. @return {Map.<K,V>} This Map itself @since 1.4

filter(bool pred(KeyValuePair<K, V>)) → Map<K, V>

Available on Map<K, V>, provided by the Map$Typings extension

Call the given predicate on each key-value pair in the collection and for each pair that it returns true, add the key-value association in a new Map.

first() → KeyValuePair<K, V>

Available on Map<K, V>, provided by the Map$Typings extension

Returns the first key/value pair in the collection, or null if there is none. @return {KeyValuePair.<K,V>} This returns null if there are no items in the collection. @since 1.4

get(K key) → V?

Available on Map<K, V>, provided by the Map$Typings extension

Returns the value associated with a key. @param {K} key The key to look up in the Map. @return {V|null} The value associated with the given key, or null if not present in the Map.

getValue(K key) → V?

Available on Map<K, V>, provided by the Map$Typings extension

Returns the value associated with a key. @param {K} key The key to look up in the Map. @return {V|null} The value associated with the given key, or null if not present in the Map.

has(K key) → bool

Available on Map<K, V>, provided by the Map$Typings extension

Returns whether the given key is in this Map. @param {K} key The key to look up in the Map. @return {boolean} Whether or not the key is contained within the Map.

map<S>(S func(KeyValuePair<K, V>)) → Map<K, S>

Available on Map<K, V>, provided by the Map$Typings extension

Call the given function on each key-value pair in the collection and associate the key with the result of the function in a new Map.

noSuchMethod(Invocation invocation) → dynamic

Invoked when a nonexistent method or property is accessed.

inherited

remove(K key) → bool

Available on Map<K, V>, provided by the Map$Typings extension

Removes a key (if found) from the Map.

set(K key, V val) → Map<K, V>

Available on Map<K, V>, provided by the Map$Typings extension

Adds a key-value association to the Map, or replaces the value associated with the key if the key was already present in the map.

toArray() → Array<KeyValuePair<K, V>>

Available on Map<K, V>, provided by the Map$Typings extension

Produces a JavaScript Array of key/value pair objects from the contents of this Map. @return {Array.<KeyValuePair.<K,V>>} A copy of the Map in Array form, each element being an Object with 'key' and 'value' properties.

toKeySet() → Set<K>

Available on Map<K, V>, provided by the Map$Typings extension

Produces a Set that provides a read-only view onto the keys of this Map. The collection of keys is not copied. @return {Set.

toString() → String

A string representation of this object.

inherited

toString$() → String

Available on Map<K, V>, provided by the Map$Typings extension

@return {string}

Operators

operator ==(Object other) → bool

The equality operator.

inherited