In TypeScript, the Set is a new data structure introduced in ES6 that stores a group/collection of unique values. The key feature of a set is that it does not allow duplicate values, but it stores only keys, not key-value pairs. In this article, we will explore How to Create a Set in TypeScript.
Create a TypeScript Set
To Create a Set in TypeScript, simply use the “Set” constructor.
let gender = new Set<string>(); gender = new Set<string>(['Male', 'Female']); console.log(gender);
Output :
Set(2) { 'Male', 'Female' }
Set Methods
| Methods | Description |
| Set.add(value) | Add the specified value to the Set. |
| set.has(value) | Checks the existence of the specified value in the Set, if it is the value present in the function it returns true or else it returns false. |
| set.delete(value) | Deletes the specified value from the Set. |
| set.clear() | Clears all the values from the Set. |
| set.size | Checks the existence of the specified value in the Set, if it is value present in the function it returns true or else it returns false. |
| set.values() | Returns an iterator with the values of the set |
| set.keys() | Returns an iterator with the values of the ‘Set’. Returns the same result as the values() function. |
| set.entries() | Return an iterator object with value/value pairs. |
| Set.forEach() | Invokes a callback on each value pair. |
Set Method Examples
How to Add an Element to a ‘Set’?
You can add elements to a Set using the provided add function.
// Create a Set let setEntries = new Set<number>(); // To Add values setEntries.add(100); setEntries.add(101); setEntries.add(102); setEntries.add(103).add(104).add(105).add(106).add(107);
How to check if a Set contains a key?
Check the existence of the specified value in the Set, using the provided function ‘has’
// check value is present or not setEntries.has(103); setEntries.has(110);
Get the Size of the Set?
// Get Set Size setEntries.size;
Delete a value from Set?
// Remove a value from Set setEntries.delete(102);
How to Remove all entries in Set?
// Clear all Set Values setEntries.clear();
How to iterate over a Set?
We can iterate over a Set using the for-of and forEach loops.
Using for-of
let Setvalues = new Set<number>();
// Add value to Set
Setvalues.add(201);
Setvalues.add(202).add(203).add(204).add(205);
// or
const Setvalues1 = new Set([500,501,502,503,504]);
//iterate Set with for-of
for (let val of Setvalues){
console.log(val);
}
Using forEach
// iterate entries with forEach
Setvalues.forEach(function(val){
console.log(val);
});
//alternatively yo can use the built -in Javascript forEach function
Setvalues.forEach(val=>console.log(val));
More article – How to Create a TypeScript Map
