Introduction
A Set object stores unique values of any type. A value can only ever occur once in a Set and is therefore unique in a Set. You can also iterate through a Set in the order in which items were successfully added.
Creating a new Set object
You create a new Set object with new Set().
const mySet = new Set();
Adding a value to a set
You can add a value to a set with the add method.
const mySet = new Set();
mySet.add('a');
// mySet is now ['a']
mySet.add('1');
// mySet is now ['a', 1]
Check if a value exists
You can check if a value exists in a Set with the has method.
const mySet = new Set();
mySet.add('a');
// mySet is now ['a']
mySet.has('a');
// Returns true because 'a' is in the set
mySet.has('b');
// Returns false because 'b' is not in the set
Delete an item from a set
You can delete an item from a set with the delete method.
const mySet = new Set();
mySet.add('a');
// mySet is now ['a']
mySet.delete('a');
// 'a' is now deleted from the set
Getting the number of items in a set
You can get the number of items in a set with the size method.
mySet.add('a');
mySet.add('b');
// mySet is now ['a', 'b']
console.log(mySet.size);
// Logs:
// 2
Lesson task
Being aware of a Set can be greatly advantageous to your career when the rare need arises that you need to make use of a Set.
Goal
To be able to make use of a Set.
Brief
Complete the Level 1 Process.
NOTE: Lesson tasks do not get submitted on Moodle and are not assessed by tutors. They are mainly there for you to practise what you have learned in the lesson.
Level 1 process
-
Create a new set called
values. -
Try adding the following values:
1,2,2,2,3,4. -
Check the length of the set.
-
Check that the set has the value of
1. -
Check that the set has the value of
a.