js map key value code example

Example 1: map through keys javascript

var myObject = { 'a': 1, 'b': 2, 'c': 3 };

Object.keys(myObject).map(function(key, index) {
  myObject[key] *= 2;
});

console.log(myObject);
// => { 'a': 2, 'b': 4, 'c': 6 }

Example 2: key value in map JavaScript mapping object

const map = {"a": 1, "b": 2, "c": 3};
const mapped = Object.entries(map).map(([k,v]) => `${k}_${v}`);
console.log(mapped);

Example 3: initialize a map js

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

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

Example 4: 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 5: map through keys javascript

var myObject = { 'a': 1, 'b': 2, 'c': 3 };

for (var key in myObject) {
  if (myObject.hasOwnProperty(key)) {
    myObject[key] *= 2;
  }
}

console.log(myObject);
// { 'a': 2, 'b': 4, 'c': 6 }

Example 6: map in javascript

['elem', 'another', 'name'].map((value, index, originalArray) => { 
  console.log(.....)
});