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JS Functions
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JS Async
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JavaScript Sets
A JavaScript Set is a collection of unique values.
Each value can only occur once in a Set.
A Set can hold any value of any data type.
Set Methods
| Method | Description |
|---|---|
| new Set() | Creates a new Set |
| add() | Adds a new element to the Set |
| delete() | Removes an element from a Set |
| has() | Returns true if a value exists |
| clear() | Removes all elements from a Set |
| forEach() | Invokes a callback for each element |
| values() | Returns an Iterator with all the values in a Set |
| keys() | Same as values() |
| entries() | Returns an Iterator with the [value,value] pairs from a Set |
| Property | Description |
|---|---|
| size | Returns the number elements in a Set |
How to Create a Set
You can create a JavaScript Set by:
- Passing an Array to
new Set() - Create a new Set and use
add()to add values - Create a new Set and use
add()to add variables
The new Set() Method
Pass an Array to the new Set() constructor:
Example
// Create a Set
const letters = new Set(["a","b","c"]);
Create a Set and add literal values:
Example
// Create a Set
const letters = new Set();
// Add Values to the
Set
letters.add("a");
letters.add("b");
letters.add("c");
Create a Set and add variables:
Example
// Create Variables
const a = "a";
const b = "b";
const c = "c";
// Create a Set
const letters = new Set();
// Add Variables to the
Set
letters.add(a);
letters.add(b);
letters.add(c);
The add() Method
Example
letters.add("d");
letters.add("e");
If you add equal elements, only the first will be saved:
Example
letters.add("a");
letters.add("b");
letters.add("c");
letters.add("c");
letters.add("c");
letters.add("c");
letters.add("c");
letters.add("c");