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30 Days of JAVASCRIPT #8/30

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Shaik Asif
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3.Sets and Maps data structures

Maps and sets are two important data structures in JavaScript that were introduced in ECMAScript 2015.

In this blog post, we will cover the following topics:

  • What is a Set?

  • How to create a Set

  • Properties and methods of a Set

  • What is a Map?

  • How to create a Map

  • Properties and methods of a Map

  • Example code

What is a Set?

A set is a collection of unique values of any type. Sets are iterable, which means we can loop through them using afor...ofloop or theforEach()method. Sets are useful when we want to store a collection of values without duplicates.

How to create a Set

To create a set, we use thenewkeyword followed by theSet()constructor. For example, we can create a set of numbers as follows:

const numbers = new Set([1, 2, 3, 4, 5]);

Properties and methods of a Set

Sets have several properties and methods that we can use to manipulate them. Here are some of the most commonly used ones:

  • add(value): adds a new value to the set

  • has(value): returns a boolean indicating whether the set contains the specified value

  • delete(value): removes the specified value from the set

  • clear(): removes all values from the set

  • size: returns the number of values in the set

What is a Map?

A map is a collection of key-value pairs where the keys can be of any type. Maps are iterable, which means we can loop through them using afor...ofloop or theforEach()method. Maps are useful when we want to store a collection of values that are associated with specific keys.

How to create a Map

To create a map, we use thenewkeyword followed by theMap()constructor. For example, we can create a map of people's ages as follows:

const ages = new Map([
  ["John", 30],
  ["Jane", 25],
  ["Bob", 40]
]);

Properties and methods of a Map

Maps have several properties and methods that we can use to manipulate them. Here are some of the most commonly used ones:

  • set(key, value): sets the value of the specified key

  • get(key): returns the value associated with the specified key

  • has(key): returns a boolean indicating whether the map contains the specified key

  • delete(key): removes the specified key-value pair from the map

  • clear(): removes all key-value pairs from the map

  • size: returns the number of key-value pairs in the map

Example code

Here's an example code that demonstrates the creation, manipulation, and iteration of sets and maps:

// Create a set of numbers
const numbers = new Set([1, 2, 3, 4, 5]);

// Add a new number to the set
numbers.add(6);

// Check if the set contains a specific number
console.log(numbers.has(3)); // Output: true

// Remove a number from the set
numbers.delete(4);

// Loop through the set using forEach()
numbers.forEach(number => {
  console.log(number);
});

// Create a map of people's ages
const ages = new Map([
  ["John", 30],
  ["Jane", 25],
  ["Bob", 40]
]);

// Set the age of a specific person
ages.set("Mary", 35);

// Get the age of a specific person
console.log(ages.get("John")); // Output: 30

// Check if the map contains a specific person
console.log(ages.has("Bob")); // Output: true

// Remove a person from the map
ages.delete("Jane");

// Loop through the map using for...of
for (const [person, age] of ages) {
  console.log(`${person} is ${age} years old`);
}

In conclusion, sets and maps are powerful data structures in JavaScript that allow us to store and manipulate collections of values in a simple and organized way. They have many useful properties and methods that make them versatile and easy to use.

JavaScript