readme.md

Sets

Now we are going to move on to sets. A set is a collection of unique values. A set can contain any data type. You can loop through a set in insertion order. Insertion order is the order in which the values were added to the set. A set is similar to an array, but a set is not indexed and does not contain duplicate values.

Creating a Set

To create a set, we use the new keyword and the Set() constructor. Let's create a set called nameSet:

const nameSet = new Set();

We can also pass an array to the Set() constructor. The values in the array will be added to the set. We can create a set with some values like this:

const nameSet = new Set(['John', 'Jane', 'Joe']);

Let's log the set:

console.log(nameSet); // Set { 'John', 'Jane', 'Joe' }

We can see that the set has three values. Let's create a set with some duplicate values:

const nameSet = new Set(['John', 'Jane', 'Joe', 'Jane', 'Joe']);

Let's log the set:

console.log(nameSet); // Set { 'John', 'Jane', 'Joe' }

We can see that even though we added duplicate values to the set, the set does not contain any duplicate values. The set only contains unique values, which can be very useful.

Adding Data

To add data to a set, we use the add() method. Let's add some values to the nameSet set:

nameSet.add('Jack');
nameSet.add('Jill');

Let's log the set:

console.log(nameSet); // Set { 'John', 'Jane', 'Joe', 'Jack', 'Jill' }

Check for a Value

To check for a value in a set, we use the has() method. Let's check if the set contains the value 'Jack':

console.log(nameSet.has('Jack')); // true

Deleting Data

To delete data from a set, we use the delete() method. Let's delete the value 'Jack' from the set:

nameSet.delete('Jack');

Let's log the set:

console.log(nameSet); // Set { 'John', 'Jane', 'Joe', 'Jill' }

Getting the Size of a Set

To get the size of a set, we use the size property. Let's log the size of the nameSet set:

console.log(nameSet.size); // 4

Getting All Values from a Set

To get all values from a set, we use the values() method. Let's log all values from the nameSet set:

console.log(nameSet.values()); // [Set Iterator] { 'John', 'Jane', 'Joe', 'Jill' }

We can see that the values() method returns a set iterator. A set iterator is an object that contains the values from the set. We can use a for...of loop to loop through the set iterator and log each value

Looping Through a Set

To loop through a set, we can use the for...of loop. Let's loop through the nameSet set and log each value:

for (const value of nameSet) {
  console.log(value);
}

Converting a Set to an Array

To convert a set to an array, we use the Array.from() method. Let's convert the nameSet set to an array:

const nameArray = Array.from(nameSet);
console.log(nameArray); // [ 'John', 'Jane', 'Joe', 'Jill' ]

Converting an Array to a Set

To convert an array to a set, we use the Set() constructor. Let's convert the nameArray array to a set:

const nameSet = new Set(nameArray);
console.log(nameSet); // Set { 'John', 'Jane', 'Joe', 'Jill' }

Deleting All Data from a Set

To delete all data from a set, we use the clear() method. Let's delete all data from the nameSet set:

nameSet.clear();

Let's try some challenges using sets.