JavaScript Set Reference
A JavaScript Set is a collection of unique values.
Each value can only occur once in a Set.
The values can be of any type, primitive values or objects.
How to Create a Set
You can create a JavaScript Set by:
- Passing an Array to
new Set() - Create a Set and use
add()to add values
Example 1
Pass an Array to the new Set() constructor:
// Create a Set
const letters = new Set(["a","b","c"]);
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Example 2
Create a Set and add values:
// Create a Set
const letters = new Set();
// Add Values to the Set
letters.add("a");
letters.add("b");
letters.add("c");
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JavaScript Set Methods and Properties
| Method | Description |
|---|---|
| new Set() | Creates a new Set |
| add() | Adds a new element to the Set |
| clear() | Removes all elements from a Set |
| delete() | Removes an element from a Set |
| entries() | Returns an Iterator with the [value,value] pairs from a Set |
| forEach() | Invokes a callback for each element |
| has() | Returns true if a value exists |
| keys() | Same as values() |
| values() | Returns an Iterator with the values in a Set |
Sets have only one property:
| Property | Description |
|---|---|
| size | Returns the number of elements in a Set |
The new Set() Method
Pass an Array to the new Set() constructor:
Listing Set Elements
You can list all Set elements (values) with a for..of loop:
Example
// Create a Set
const letters = new Set(["a","b","c"]);
// List all Elements
let text = "";
for (const x of letters) {
text += x;
}
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