TypeScript Set

TypeScript set is a new data structure added in ES6 version of JavaScript. It allows us to store distinct data (each value occur only once) into the List similar to other programming languages. Sets are a bit similar to maps, but it stores only keys, not the key-value pairs.

Create Set

We can create a set as below.

Set methods

The TypeScript set methods are listed below.

SN	Methods	Descriptions
1.	set.add(value)	It is used to add values in the set.
2.	set.has(value)	It returns true if the value is present in the set. Otherwise, it returns false.
3.	set.delete()	It is used to remove the entries from the set.
4.	set.size()	It is used to returns the size of the set.
5.	set.clear()	It removes everything from the set.

Example

We can understand the set methods from the following example.

let studentEntries = new Set();
 
//Add Values
studentEntries.add("John");
studentEntries.add("Peter");
studentEntries.add("Gayle");
studentEntries.add("Kohli"); 
studentEntries.add("Dhawan"); 

//Returns Set data
console.log(studentEntries); 
 
//Check value is present or not
console.log(studentEntries.has("Kohli"));      
console.log(studentEntries.has(10));      
 
//It returns size of Set
console.log(studentEntries.size);  
 
//Delete a value from set
console.log(studentEntries.delete("Dhawan"));    
 
//Clear whole Set
studentEntries.clear(); 

//Returns Set data after clear method.
console.log(studentEntries);

Output:

When we execute the above code snippet, it returns the following output.

Chaining of Set Method

TypeScript set method also allows the chaining of add() method. We can understand it from the below example.

Example

let studentEntries = new Set();
 
//Chaining of add() method is allowed in TypeScript
studentEntries.add("John").add("Peter").add("Gayle").add("Kohli");

//Returns Set data
console.log("The List of Set values:");
console.log(studentEntries);

Output:

Iterating Set Data

We can iterate over set values or entries by using 'for...of' loop. The following example helps to understand it more clearly.

Example

let diceEntries = new Set();

diceEntries.add(1).add(2).add(3).add(4).add(5).add(6);
 
//Iterate over set entries
console.log("Dice Entries are:"); 
for (let diceNumber of diceEntries) {
    console.log(diceNumber); 
}
 
// Iterate set entries with forEach
console.log("Dice Entries with forEach are:"); 
diceEntries.forEach(function(value) {
  console.log(value);   
});

Output: