Update an element in a Map using JavaScript

You can use the set() method to update an element value in a Map object. The set() method adds or updates an element with the specified key and value and returns the Map object.

const map = new Map([
  ['name', 'Alex'],
  ['scores', [75, 87]],
  ['bio', { age: 27, country: 'Pakistan' }]
])

console.log(map)
// Map(3) {
//     'name' => 'Alex',
//     'scores' => [ 75, 87 ],
//     'bio' => { age: 27, country: 'Pakistan' }
// }

// Update name (STRING)
map.set('name', 'Alex Hales')
console.log(map.get('name')) // Alex Hales

// Update scores (ARRAY)
map.set('scores', [...map.get('scores'), 99])
console.log(map.get('scores')) // [ 75, 87, 99 ]

// Update bio (OBJECT)
map.set('bio', { ...map.get('bio'), job: 'Engineer' })

console.log(map.get('bio'))
// { age: 27, country: 'Pakistan', job: 'Engineer' }

The set() method takes two parameters: the element key and the value. If the Map object already contains the key, it updates the value. Otherwise, it adds a key-value pair to the Map object.

You can also use the set() method to add elements to a Map object:

const map = new Map([
  ['name', 'Alex'],
  ['scores', [75, 87]],
  ['bio', { age: 27, country: 'Pakistan' }]
])

map.set('email', 'alex@example.com')

console.log(map)
// Map(4) {
//     'name' => 'Alex',
//     'scores' => [ 75, 87 ],
//     'bio' => { age: 27, country: 'Pakistan' },
//     'email' => 'alex@example.com'
// }

Read this article to learn more about the Map object and how to use it to create collections of key-value pairs in JavaScript.

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