freeCodeCamp/guide/english/certifications/coding-interview-prep/data-structures/create-a-set-class/index.md

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title: Create a Set Class
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# Create a Set Class

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## Problem Explanation
- A Set is an abstract data structure.
- It can store unique value and the collection is unordered.
- In this challenge, we have to implement `.add()` method. This method should only add unique values to `collection`.
  - The method should return `true`, if the value is sucessfully added to the collection, otherwise it should return `false`.


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## Solutions
<details><summary>Solution 1 (Click to Show/Hide)</summary>

```js
function Set() {
  // the var collection will hold our set
  var collection = [];
  // this method will check for the presence of an element and return true or false
  this.has = function(element) {
    return collection.indexOf(element) !== -1;
  };
  // this method will return all the values in the set
  this.values = function() {
    return collection;
  };
  this.add = function(el) {
    return this.has(el) ? false : Boolean(collection.push(el));
  };
}
```

#### Relevant Links
- [Wikipedia](https://en.wikipedia.org/wiki/Set_(abstract_data_type))

</details>