Map[@@iterator]( ) method is used to make Map iterable. Map[@@iterator]( ) method returns iterator object which iterates over all code points of Map. Map[@@iterator]( ) is built-in property of Map.
We can use this method by creating Map iterator. We can make Map iterator by calling the @@iterator property. In place of @@iterator, we can use Symbol.iterator constant.
Syntax:
const iter = Map[ Symbol.iterator]();
Parameters: This property does not accept any parameters. Return Value: It returns an iterator to iterating code point of iterator objects.
Example:
JavaScript
<script> const m = new Map(); m.set(0, "a") m.set(2, "b") m.set(3, "c") const iterator = m[Symbol.iterator](); let itr = iterator.next() for (let i = 0; i < script m.size; i++) { console.log(itr.value, itr.done) itr = iterator.next() }</script> |
Output:
[0 : 'a'] false [1 : 'b'] false [2 : 'c'] false
Example: We can use Map.prototype[@@iterator] method with assign Map to the iterator. We can use for loop to iterate over the code point of Map. The for-of loop uses an iterator to iterate over values of Map.
Javascript
<script> const m = new Map(); m.set(0, "a") m.set(2, "b") m.set(3, "c") const iterator = m[Symbol.iterator](); let itr = iterator.next() for (let i = 0; i < m.size; i++) { console.log(itr.value) itr = iterator.next() } console.log("iterating with for-of loop : ") for (let i of m) { console.log(i) }</script> |
Output:
[0 : 'a'] [1 : 'b'] [2 : 'c'] iterating with for-of loop : [0 : 'a'] [1 : 'b'] [2 : 'c']
Supported Browsers:
- Chrome 38 and above
- Edge 12 and above
- Firefox 13 and above
- Internet Explorer 11 and above
- Opera 25 and above
- Safari 8 and above
We have a complete list of Javascript Map methods, to check those please go through this JavaScript MapComplete Reference article.
