day28

Day 28: Sets

Hello and welcome back to the 28th day of DailyJS. Today's topic is Set.

If you are coming from Python language, you might be familiar with the concept of sets.

Set objects are collections of values. You can iterate through the elements of a set in insertion order. A value in the Set may only occur once; it is unique in the Set's collection.

In layman terms, a set can be seen as a collection of elements where each element is unique.

Syntax

Similar to Map, Set is also initialized through a constructor.

var mySet = new Set();

Some important methods -

1. Set.prototype.add(element)
2. Set.prototype.delete(element)
3. Set.prototype.clear()
4. Set.prototype.has(element)
5. Set.prototype.entries()

Example

/**
 * Set in JS
 */

var students = new Set (["John", "Kepler", "Amanda"]);
console.log (students);

// Add
students.add ("Ronaldo");
students.add ("Johny");
students.add ("John"); // Won't be added
console.log (students);

// Delete
students.delete ("Johny");
console.log (students);

// Clear
students.clear ();
console.log (students); // Empty set

// Add some values
students.add ("Ronaldo");
students.add ("Johny");
students.add ("John");

// Entries
var entries = students.entries ();
console.log (entries);

// Has
console.log ("Has John?", students.has ("John"));