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  • Book Overview & Buying Lo-Dash Essentials
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Lo-Dash Essentials

Lo-Dash Essentials

By : Adam Boduch
4.8 (8)
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Lo-Dash Essentials

Lo-Dash Essentials

4.8 (8)
By: Adam Boduch
Buy this Book

Overview of this book

If you are a curious JavaScript developer interested simultaneously in tweaking the efficiency of your code, as well as improving the conciseness of it, and maintaining the readability of it, then this is the book for you. Ideally, the book is intended for readers already working on JavaScript projects and using frameworks such as jQuery and Backbone. Even if you're already using Lo-Dash, this book will show you how to use it efficiently. While extensive JavaScript experience isn't a requirement, you should have at least some prior programming experience in order to best understand the concepts presented.
Table of Contents (10 chapters)
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Preface
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Preface
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What this book covers
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What you need for this book
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Who this book is for
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Conventions
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Reader feedback
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Customer support
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1
1. Working with Arrays and Collections
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1. Working with Arrays and Collections
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The difference between arrays and collections
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Iterating over collections
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Sorting data
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Searching for data
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Slicing collections into smaller pieces
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Transforming collections
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Summary
2
2. Working with Objects
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2. Working with Objects
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Determining an object type
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Assigning and accessing properties
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Iterating over objects
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Calling methods
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Transforming objects
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Creating and cloning objects
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Summary
3
3. Working with Functions
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3. Working with Functions
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Binding function contexts
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Decorating functions
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Function constraints
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Timed execution
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Composing and currying functions
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Summary
4
4. Transformations Using Map/Reduce
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4. Transformations Using Map/Reduce
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Plucking values
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Mapping collections
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Mapping objects
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Reducing collections
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Reducing objects
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Binding contexts
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Map/reduce patterns
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Summary
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5. Assembling Chains
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5. Assembling Chains
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Creating Lo-Dash wrappers
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Building filters
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Testing truth conditions
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Counting items
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Transformations
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Intermediary results
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Keys and values
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Returning wrappers
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Summary
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6. Application Building Blocks
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6. Application Building Blocks
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Generic functions
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Generic wrappers and chains
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Composing functions
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Creating mixins
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Summary
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7. Using Lo-Dash with Other Libraries
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7. Using Lo-Dash with Other Libraries
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Modules
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jQuery
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Backbone
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Node.js
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Summary
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8. Internal Design and Performance
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8. Internal Design and Performance
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Design principles
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Improving performance
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Lazy evaluation
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Caching things
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Summary
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Index
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Index

Reducing collections

It's now time to look at reducing collections. Lo-Dash helps a lot here too, supplying functions that help us reduce arrays, objects, and anything that's thrown our way. Aside from primitives, all data structures can be reduced to something simpler.

We'll start off by looking at the common reduce cases, summing values, and such. This will be followed by the topic of filtering collections and how it relates to reducing. Then, we'll look at some more advanced computational techniques.

Summing values

Unlike other programming languages, JavaScript has no built-in mechanism to sum together an array of values. The closest we get to summing is the native Array.reduce() method, which is actually general purpose and not specifically for summing values. The Lo-Dash version of reduce is even more general purpose, and here's an example of how to use it in summing values in a collection:

var collection = [ 
    { ram: 1024, storage: 2048 },
    { ram: 2048, storage: 4096 },
    { ram...
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Tech Concepts
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Programming languages
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Lo-Dash Essentials
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