The get() method of Map instances returns a specified element from this map. If the
value that is associated to the provided key is an object, then you will get a
reference to that object and any change made to that object will effectively
modify it inside the Map object.
Syntax
get(key)
Parameters
key- : The key of the element to return from the
Mapobject.
- : The key of the element to return from the
Return value
The element associated with the specified key, or
undefined if the key can't be found in the Map object.
Examples
Using get()
const myMap = new Map();
myMap.set("bar", "foo");
console.log(myMap.get("bar")); // Returns "foo"
console.log(myMap.get("baz")); // Returns undefined
Using get() to retrieve a reference to an object
const arr = [];
const myMap = new Map();
myMap.set("bar", arr);
myMap.get("bar").push("foo");
console.log(arr); // ["foo"]
console.log(myMap.get("bar")); // ["foo"]
Note that the map holding a reference to the original object effectively means the object cannot be garbage-collected, which may lead to unexpected memory issues. If you want the object stored in the map to have the same lifespan as the original one, consider using a WeakMap.