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---
id: 587d8253367417b2b2512c6c
title: Perform a Union on Two Sets
challengeType: 1
---
## Description
< section id = 'description' >
In this exercise we are going to perform a union on two sets of data. We will create a method on our < code > Set< / code > data structure called < code > union< / code > . This method should take another < code > Set< / code > as an argument and return the < code > union< / code > of the two sets, excluding any duplicate values.
For example, if < code > setA = ['a','b','c']< / code > and < code > setB = ['a','b','d','e']< / code > , then the union of setA and setB is: < code > setA.union(setB) = ['a', 'b', 'c', 'd', 'e']< / code > .
< / section >
## Instructions
< section id = 'instructions' >
< / section >
## Tests
< section id = 'tests' >
```yml
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tests:
- text: Your < code > Set</ code > class should have a < code > union</ code > method.
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testString: assert((function(){var test = new Set(); return (typeof test.union === 'function')})());
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- text: The union of < code > ["a", "b", "c"]</ code > and < code > ["c", "d"]</ code > should return < code > ["a", "b", "c", "d"]</ code > .
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testString: assert((function(){var setA = new Set(); var setB = new Set(); setA.add('a'); setA.add('b'); setA.add('c'); setB.add('c'); setB.add('d'); var unionSetAB = setA.union(setB); var final = unionSetAB.values(); return (final.indexOf('a') !== -1 & & final.indexOf('b') !== -1 & & final.indexOf('c') !== -1 & & final.indexOf('d') !== -1 & & final.length === 4)})());
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```
< / section >
## Challenge Seed
< section id = 'challengeSeed' >
< div id = 'js-seed' >
```js
function Set() {
// the var collection will hold the 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 method will add an element to the set
this.add = function(element) {
if(!this.has(element)){
collection.push(element);
return true;
}
return false;
};
// this method will remove an element from a set
this.remove = function(element) {
if(this.has(element)){
var index = collection.indexOf(element);
collection.splice(index,1);
return true;
}
return false;
};
// this method will return the size of the set
this.size = function() {
return collection.length;
};
// change code below this line
// change code above this line
}
```
< / div >
< / section >
## Solution
< section id = 'solution' >
```js
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function Set() {
var collection = [];
this.has = function(element) {
return (collection.indexOf(element) !== -1);
};
this.values = function() {
return collection;
};
this.add = function(element) {
if(!this.has(element)){
collection.push(element);
return true;
}
return false;
};
this.remove = function(element) {
if(this.has(element)){
var index = collection.indexOf(element);
collection.splice(index,1);
return true;
}
return false;
};
this.size = function() {
return collection.length;
};
this.union = function(anotherSet){
const newSet = new Set();
const addToSet = el => newSet.add(el);
this.values().forEach(addToSet);
anotherSet.values().forEach(addToSet);
return newSet;
};
}
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```
< / section >