Explore the basics of JavaScript in greater detail to solve real-world problems.

Zero to Hero in JavaScript

This module aims to teach us how to write cleaner, more modular, and more scalable code in JavaScript by giving us an understanding of object-oriented programming (OOP). We'll start with the basics of object-oriented programming and build up to more advanced concepts such as data protection and inheritance. Along the way, we'll learn how each concept applies to JavaScript in particular, as well as how various JavaScript features make it a suitable language for object-oriented programming.

JavaScript: A Deep Dive

# Putting it all together

Now that all functions are working and ready, let’s jump into the final **`mapreduce` function**. This will be the simulation of our **MapReduce** framework. Look at the code below.

// Final
function mapreduce (friends) {
    var initial = setup(friends);
    var mapped = mapper(initial);
    var grouped = group(mapped);
    var reduced = reducer(grouped);
    return reduced;
    // return an object {(man,friend): [Friends]}
}

var arr = [
    ['A', 'B'], ['A', 'C'],
    ['A', 'D'], ['B', 'C'],
    ['B', 'D'], ['B', 'E'],
    ['C', 'D'], ['C', 'E'],
    ['D', 'E']
];

console.log(mapreduce(arr));

The code above calls a series of **functions** in the **function `mapreduce`**. The **`mapreduce` function** takes only one **argument**, `friends`, which is expected to be an **array** of **arrays**. Take the **argument**. *Pass* it to the **`setup` function** for an **object** to be **mapped** which is *assigned* to the **variable** named `initial` (**line 3**). Then take this value and *pass* it to the **`mapper` function**. *Assign* the returned value to the `mapped` **variable** (**line 4**). Now *passed* to the **`group` function**, the result is *assigned* to the `grouped` **variable** (**line 5**). Finally, the value *assigned* to the `grouped` **variable** is passed on to the `reducer` **function** for the final answer. The final answer *assigned* to **variable** `reduced` is then returned on **line 7**. 

This concludes our implementation of the  **MapReduce** framework to find mutuals among friends.

The solution to MapReduce in JavaScript for the problem "Find Mutual Friends"

Solution to Find Mutual Friends

Putting it all together