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JavaScript Maps
A Map holds key-value pairs where the keys can be any datatype.
A Map remembers the original insertion order of the keys.
A Map has a property that represents the size of the map.
Map Methods
| Method | Description |
|---|---|
| new Map() | Creates a new Map object |
| set() | Sets the value for a key in a Map |
| get() | Gets the value for a key in a Map |
| clear() | Removes all the elements from a Map |
| delete() | Removes a Map element specified by a key |
| has() | Returns true if a key exists in a Map |
| forEach() | Invokes a callback for each key/value pair in a Map |
| entries() | Returns an iterator object with the [key, value] pairs in a Map |
| keys() | Returns an iterator object with the keys in a Map |
| values() | Returns an iterator object of the values in a Map |
| Property | Description |
|---|---|
| size | Returns the number of Map elements |
How to Create a Map
You can create a JavaScript Map by:
- Passing an Array to
new Map() - Create a Map and use
Map.set()
new Map()
You can create a Map by passing an Array to the new Map()
constructor:
Example
// Create a Map
const fruits = new Map([
["apples",
500],
["bananas",
300],
["oranges",
200]
]);
Map.set()
You can add elements to a Map with the set() method:
Example
// Create a Map
const fruits = new Map();
// Set Map Values
fruits.set("apples", 500);
fruits.set("bananas", 300);
fruits.set("oranges", 200);