map node js code example

Example 1: array map javascript

const array1 = [1, 4, 9, 16];

// pass a function to map
const map1 = array1.map(x => x * 2);

console.log(map1);
// expected output: Array [2, 8, 18, 32]

Example 2: 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);

Example 3: 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 ]

Example 4: nodejs map

let wrongMap = new Map()
wrongMap['bla'] = 'blaa'
wrongMap['bla2'] = 'blaaa2'

console.log(wrongMap)  // Map { bla: 'blaa', bla2: 'blaaa2' }