Map
Map is a collection of keyed data items, just like an Object. But the main difference is that Map allows keys of any type.
| Method/Property | Description |
|---|---|
new Map() |
Creates a new Map object. |
map.set(key, value) |
Stores the value in the map object under the key. |
map.get(key) |
Returns the value associated with the key, or undefined if the key doesn't exist. |
map.has(key) |
Returns true if the map contains the key, otherwise returns false. |
map.delete(key) |
Removes the element (key/value pair) from the map specified by the key. |
map.clear() |
Removes all elements from the map. |
map.size |
Returns the number of elements (key/value pairs) in the map. |
An example of Map() with its various methods and properties is shown below.
let map = new Map();
map.set('1', 'str1'); // a string key
map.set(1, 'num1'); // a numeric key
map.set(true, 'bool1'); // a boolean key
// remember the regular Object? it would convert keys to string
// Map keeps the type, so these two are different:
alert( map.get(1) ); // 'num1'
alert( map.get('1') ); // 'str1'
alert( map.size ); // 3
The differences from a regular Object:
Any keys, objects can be keys.
Additional convenient methods, the size property.
Maps are a versatile and powerful data structure that provides key-value pairs for efficient data management. Maps are often a preferred choice over plain objects for tasks involving key-value associations, as they provide better control and performance.