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In JavaScript, a Set is a built-in object that allows you to store unique values of any data type, whether primitive values or object references. Unlike arrays, which can contain duplicate values and are ordered by index, a Set only holds distinct values, and the order of insertion is maintained.
Here are the key characteristics of a Set:
- Uniqueness: A
Set can only contain unique values. If you attempt to add a duplicate value, it will be ignored. This uniqueness is determined using the “SameValueZero” equality comparison algorithm, which is similar to the strict equality (===) operator.
- Iterable:
Set objects are iterable, which means you can use methods like forEach or for...of loop to iterate through the values.
- No Index: Unlike arrays,
Set objects do not have indexes or keys associated with their elements. You access elements directly through the Set methods.
- Methods:
Set provides methods for adding, deleting, and checking the existence of values. Common methods include add, delete, has, and clear.
Example: Here, mySet is created, values are added using the add method, and existence is checked using the has method. The delete method removes a value, and the forEach method is used to iterate over the elements.
Javascript
const mySet = new Set();
mySet.add(1);
mySet.add('Hello');
mySet.add({ key: 'value' });
console.log(mySet.has(1));
console.log(mySet.has('Hello'));
console.log(mySet.has({ key: 'value' }));
mySet.delete('Hello');
mySet.forEach(value => {
console.log(value);
});
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Output
true
true
false
1
{ key: 'value' }
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