javascript hashmap
let contacts = new Map()
contacts.set('Jessie', {phone: "213-555-1234", address: "123 N 1st Ave"})
contacts.has('Jessie') // true
contacts.get('Hilary') // undefined
contacts.set('Hilary', {phone: "617-555-4321", address: "321 S 2nd St"})
contacts.get('Jessie') // {phone: "213-555-1234", address: "123 N 1st Ave"}
contacts.delete('Raymond') // false
contacts.delete('Jessie') // true
console.log(contacts.size) // 1javascript map
array.map((item) => {
return item * 2
} // an example that will map through a a list of items and return a new array with the item multiplied by 2new map js
let utilisateurs = new Map()
utilisateurs.set('Mark Zuckerberg' ,{
email: '[email protected]',
poste: 'PDG',
})
utilisateurs.set ('bill Gates',{
email: '[email protected]' ,
poste : 'sauver le monde' ,
})
console.log(utilisateurs);maps in javascript
// Map decalaration in javaScript
const obj1 = { name: 'ismail' };
const obj2 = { name: 'sulman' };
const obj3 = { name: 'naeem' };
firstMap = new Map([
[
[obj1, [{ date: 'yesterday', price: '10$' }]], // using object as a key in the map and object inside the array
[obj2, [{ date: 'today', price: '100$' }]]
]
]);
firstMap.set(obj3, [{ date: "yesterday", price: '150$' }]); //pushing the obj to the Map
// iterating the Map
for (const entry of firstMap.entries()) {
console.log(entry);
};
console.log(firstMap);
firstMap.delete(obj3);
console.log(firstMap);initialize a map js
let map = new Map()
map['bla'] = 'blaa'
map['bla2'] = 'blaaa2'
console.log(map) // Map { bla: 'blaa', bla2: 'blaaa2' }map in javascript
// Use map to create a new array in memory. Don't use if you're not returning
const arr = [1,2,3,4]
// Get squares of each element
const sqrs = arr.map((num) => num ** 2)
console.log(sqrs)
// [ 1, 4, 9, 16 ]
//Original array untouched
console.log(arr)
// [ 1, 2, 3, 4 ]Copyright © 2021 Codeinu
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