What is the process for converting a Map into a Set and vice versa?

Question

What is the process for converting a Map into a Set and vice versa?

forEach() method uses the value variable twice for compatibility between Map and Set.

This use of the same value twice is to align with Map's callback structure. It may seem odd, but it makes replacing Map with Set easier in some cases, and vice versa.

let set = new Set(["orange", "apple", "banana"]);
        
set.forEach((value, valueAgain, set) => {
  console.log(valueAgain); //"orange", "apple", "banana"
});

My question is how Set can be converted into Set and vice versa if there are no specific methods for this scenario?

javascript foreach set

Answer 1

Answer №1

The key point here is not simply substituting a set with a map in your code. By doing so, you are essentially making changes to the code anyway, and rewriting the iteration would pose no difficulty.

However, the true advantage lies in being able to write code that can accommodate both scenarios simultaneously. Consider this example:

function displayItems(collection) {
    collection.forEach((value, key) => {
        console.log(key, value);
    });
}

const set = new Set(["orange", "apple", "banana"]);
const map = new Map([[1, "peach"], [2, "pear"]]);

displayItems(set); // functions correctly
displayItems(map); // performs the same way

Answer 2

The key point here is not simply substituting a set with a map in your code. By doing so, you are essentially making changes to the code anyway, and rewriting the iteration would pose no difficulty.

However, the true advantage lies in being able to write code that can accommodate both scenarios simultaneously. Consider this example:

function displayItems(collection) {
    collection.forEach((value, key) => {
        console.log(key, value);
    });
}

const set = new Set(["orange", "apple", "banana"]);
const map = new Map([[1, "peach"], [2, "pear"]]);

displayItems(set); // functions correctly
displayItems(map); // performs the same way

Answer 3

Answer №2

This piece of code demonstrates how you can use the same function callback both for a Set and a Map data structure. It showcases the forEach method being used on a Set containing fruit names and a Map containing vegetable names with their corresponding quantities.

const fruits = new Set(["oranges", "apples", "bananas"]);
const vegetables = new Map([
  ['cucumber', 500],
  ['tomatoes', 350],
  ['onion',    50]
]);
const logItem = (value, key) => console.log(value, key);
fruits.forEach(logItem)
// oranges oranges
// apples apples
// bananas bananas

vegetables.forEach(logItem)
// 500 cucumber
// 350 tomatoes
// 50 onion

Answer 4

This piece of code demonstrates how you can use the same function callback both for a Set and a Map data structure. It showcases the forEach method being used on a Set containing fruit names and a Map containing vegetable names with their corresponding quantities.

const fruits = new Set(["oranges", "apples", "bananas"]);
const vegetables = new Map([
  ['cucumber', 500],
  ['tomatoes', 350],
  ['onion',    50]
]);
const logItem = (value, key) => console.log(value, key);
fruits.forEach(logItem)
// oranges oranges
// apples apples
// bananas bananas

vegetables.forEach(logItem)
// 500 cucumber
// 350 tomatoes
// 50 onion

What is the process for converting a Map into a Set and vice versa?

Answer №1

Answer №2

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