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Merge pull request #12 from Bouncey/feat/featureBuild

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Feat/feature build
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Stuart Taylor
2018-04-13 16:45:21 +01:00
committed by Mrugesh Mohapatra
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packages/learn/src/introductions/javascript-algorithms-and-data-structures/basic-data-structures/index.md
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---
title: Introduction to Objects
title: Introduction to the Basic Data Structure Challenges
block: Basic Data Structures
superBlock: JavaScript Algorithms and Data Structures
---
## Introduction to Objects
The next data structure we will discuss is the JavaScript <dfn>object</dfn>. Like arrays, objects are a fundamental part of JavaScript. However, it is probably safe to say that objects surpass arrays in flexibility, usefulness and in their overall importance to the language &mdash; in fact, you may have heard this line before: 'In JavaScript, everything is an object.'<br><br>While an understanding of objects is important to understand the inner workings of JavaScript functions or JavaScript's object-oriented capabilities, JavaScript objects at a basic level are actually just <dfn>key-value pair</dfn> stores, a commonly used data structure across almost all programming languages. Here, we will confine our discussion to JavaScript objects in this capacity.
Key-value pair data structures go by different names depending on the language and the specific details of the data structure. The terms <dfn>dictionary</dfn>, <dfn>map</dfn>, and <dfn>hash table</dfn> all refer to the notion of a data structure in which specific keys, or properties, are mapped to specific values.<br><br>Objects, and other similar key-value pair data structures, offer some very useful benefits. One clear benefit is that they allow us to structure our data in an intuitive way; properties can be nested to an arbitrary depth, and values can be anything, including arrays and even other objects.<br><br>Largely due to this flexibility, objects are also the foundation for <dfn>JavaScript Object Notation</dfn>, or <dfn>JSON</dfn>, which is a widely used method of sending data across the web.
Another powerful advantage of key-value pair data structures is <dfn>constant lookup time</dfn>. What this means, is that when you request the value of a specific property, you will get the value back in the same amount of time (theoretically) regardless of the number of entries in the object. If you had an object with 5 entries or one that held a collection of 1,000,000, you could still retrieve property values or check if a key exists in the same amount of time.<br><br>The reason for this fast lookup time, is that internally, the object is storing properties using a hashing mechanism which allows it to know exactly where it has stored different property values. If you want to learn more about this please take a look at the optional Advanced Data Structures challenges. All you should remember for now is that <strong>performant access to flexibly structured data make key-value stores very attractive data structures useful in a wide variety of settings</strong>.
<br><br>In JavaScript, objects are written as comma-separated lists of key-value pairs, wrapped in curly brackets, with each key and its assigned value separated by a colon:<br> <code>{ key1: 'val-1', key2: 'val-2' }</code><br><br>In the next few challenges, we will examine JavaScript objects more closely, and take a look at <dfn>methods</dfn> and techniques that allow us to access, store, and manipulate an object's data.<br><br>Note that throughout the scope of this discussion, and in general when considering JavaScript objects, the terms <dfn>key</dfn> and <dfn>property</dfn> will be used interchangeably.
## Introduction to the Basic Data Structure Challenges
This is a stub introduction