Important methods in Map with example

Map is like key value pair concept (like an Object). But Map allows keys as any type. Remember object allows only string key.

Note: ES6 map is different. Do not make confuse yourself.

Main methods are below,

      new Map() – creates the map.

     map.set(key, value) – stores key and value.

     map.get(key) – returns the value by the key. Suppose If key doesn’t exist undefined will be  returned.

     map.has(key) – returns true if the key exists, else false will be returned.

     map.delete(key) – removes the value by the key.

     map.clear() – clears the map.

     map.size – returns the current element count.

Simple Example I:

let map = new Map();

map.set('1', 'stringOne');   // a string key
map.set(1, 'number1');     // a numeric key
map.set(true, 'booleanValueTrue'); // a boolean key

alert( map.get(1)   ); // 'number1'
alert( map.get('1') ); // 'stringOne'
alert( map.get(true) ); // 'booleanValueTrue
alert( map.size ); // 3

Note: See the above example, Keys are not converted to string.