Learn to Write Functional Javascript

Understanding Foundations of Functional Programming 4 lectures 49:29 The Course Overview This video provides an overview of the entire course The Unbreakable Function JavaScript has traditionally been taught by the "Imperative or Procedural Programming" paradigms where functions ("procedures") perform tasks and modify a shared state. This can cause unpredictable behavior and hard to track bugs, especially as programs grow. Pure functions alleviate many problems of traditional programming paradigms and form the foundations of Functional Programming.

• A pure function does not change values outside of itself
• Given the same inputs, a pure function returns the same output

Thinking of Functions in Terms of Their Return Values Pure functions, like mathematical functions, always return the same value when given the same inputs, so the two are interchangeable. Functional Programming is expressive, we think less about what's happening inside functions and focus more on relations between function inputs and their outputs.

• Pure functions have a unique mappings from input to output
• Running pure functions inline is representative of a unique value
• Pure functions calling other pure functions won't complicate our mental model

How to Identify and Encapsulate Impurities within Our Programs Every program has impure functions; they are the only ticket in town for reading, writing and displaying information. In order to protect the benefits, we've gained by writing pure functions; we'll begin looking at how we can isolate impure code while still using it to feed us information.

• Identify which parts of our program is pure and which are impure
• Pure functions can return impure functions without breaking referential transparency
• We can defer impure operations and pass results into pure functions as dependencies

Understanding Foundations of Functional Programming 4 lectures 49:29 The Course Overview This video provides an overview of the entire course The Unbreakable Function JavaScript has traditionally been taught by the "Imperative or Procedural Programming" paradigms where functions ("procedures") perform tasks and modify a shared state. This can cause unpredictable behavior and hard to track bugs, especially as programs grow. Pure functions alleviate many problems of traditional programming paradigms and form the foundations of Functional Programming.

• A pure function does not change values outside of itself
• Given the same inputs, a pure function returns the same output

Thinking of Functions in Terms of Their Return Values Pure functions, like mathematical functions, always return the same value when given the same inputs, so the two are interchangeable. Functional Programming is expressive, we think less about what's happening inside functions and focus more on relations between function inputs and their outputs.

• Pure functions have a unique mappings from input to output
• Running pure functions inline is representative of a unique value
• Pure functions calling other pure functions won't complicate our mental model

How to Identify and Encapsulate Impurities within Our Programs Every program has impure functions; they are the only ticket in town for reading, writing and displaying information. In order to protect the benefits, we've gained by writing pure functions; we'll begin looking at how we can isolate impure code while still using it to feed us information.

• Identify which parts of our program is pure and which are impure
• Pure functions can return impure functions without breaking referential transparency
• We can defer impure operations and pass results into pure functions as dependencies

The Course Overview This video provides an overview of the entire course The Course Overview This video provides an overview of the entire course The Course Overview This video provides an overview of the entire course The Course Overview This video provides an overview of the entire course This video provides an overview of the entire course This video provides an overview of the entire course The Unbreakable Function JavaScript has traditionally been taught by the "Imperative or Procedural Programming" paradigms where functions ("procedures") perform tasks and modify a shared state. This can cause unpredictable behavior and hard to track bugs, especially as programs grow. Pure functions alleviate many problems of traditional programming paradigms and form the foundations of Functional Programming.

• A pure function does not change values outside of itself
• Given the same inputs, a pure function returns the same output

The Unbreakable Function JavaScript has traditionally been taught by the "Imperative or Procedural Programming" paradigms where functions ("procedures") perform tasks and modify a shared state. This can cause unpredictable behavior and hard to track bugs, especially as programs grow. Pure functions alleviate many problems of traditional programming paradigms and form the foundations of Functional Programming.

• A pure function does not change values outside of itself
• Given the same inputs, a pure function returns the same output

The Unbreakable Function JavaScript has traditionally been taught by the "Imperative or Procedural Programming" paradigms where functions ("procedures") perform tasks and modify a shared state. This can cause unpredictable behavior and hard to track bugs, especially as programs grow. Pure functions alleviate many problems of traditional programming paradigms and form the foundations of Functional Programming.

• A pure function does not change values outside of itself
• Given the same inputs, a pure function returns the same output

The Unbreakable Function JavaScript has traditionally been taught by the "Imperative or Procedural Programming" paradigms where functions ("procedures") perform tasks and modify a shared state. This can cause unpredictable behavior and hard to track bugs, especially as programs grow. Pure functions alleviate many problems of traditional programming paradigms and form the foundations of Functional Programming.

• A pure function does not change values outside of itself
• Given the same inputs, a pure function returns the same output

JavaScript has traditionally been taught by the "Imperative or Procedural Programming" paradigms where functions ("procedures") perform tasks and modify a shared state. This can cause unpredictable behavior and hard to track bugs, especially as programs grow. Pure functions alleviate many problems of traditional programming paradigms and form the foundations of Functional Programming.

• A pure function does not change values outside of itself
• Given the same inputs, a pure function returns the same output

JavaScript has traditionally been taught by the "Imperative or Procedural Programming" paradigms where functions ("procedures") perform tasks and modify a shared state. This can cause unpredictable behavior and hard to track bugs, especially as programs grow. Pure functions alleviate many problems of traditional programming paradigms and form the foundations of Functional Programming.

• A pure function does not change values outside of itself
• Given the same inputs, a pure function returns the same output

Thinking of Functions in Terms of Their Return Values Pure functions, like mathematical functions, always return the same value when given the same inputs, so the two are interchangeable. Functional Programming is expressive, we think less about what's happening inside functions and focus more on relations between function inputs and their outputs.

• Pure functions have a unique mappings from input to output
• Running pure functions inline is representative of a unique value
• Pure functions calling other pure functions won't complicate our mental model

Thinking of Functions in Terms of Their Return Values Pure functions, like mathematical functions, always return the same value when given the same inputs, so the two are interchangeable. Functional Programming is expressive, we think less about what's happening inside functions and focus more on relations between function inputs and their outputs.

• Pure functions have a unique mappings from input to output
• Running pure functions inline is representative of a unique value
• Pure functions calling other pure functions won't complicate our mental model

Thinking of Functions in Terms of Their Return Values Pure functions, like mathematical functions, always return the same value when given the same inputs, so the two are interchangeable. Functional Programming is expressive, we think less about what's happening inside functions and focus more on relations between function inputs and their outputs.

• Pure functions have a unique mappings from input to output
• Running pure functions inline is representative of a unique value
• Pure functions calling other pure functions won't complicate our mental model

Thinking of Functions in Terms of Their Return Values Pure functions, like mathematical functions, always return the same value when given the same inputs, so the two are interchangeable. Functional Programming is expressive, we think less about what's happening inside functions and focus more on relations between function inputs and their outputs.

• Pure functions have a unique mappings from input to output
• Running pure functions inline is representative of a unique value
• Pure functions calling other pure functions won't complicate our mental model

Pure functions, like mathematical functions, always return the same value when given the same inputs, so the two are interchangeable. Functional Programming is expressive, we think less about what's happening inside functions and focus more on relations between function inputs and their outputs.

• Pure functions have a unique mappings from input to output
• Running pure functions inline is representative of a unique value
• Pure functions calling other pure functions won't complicate our mental model

Pure functions, like mathematical functions, always return the same value when given the same inputs, so the two are interchangeable. Functional Programming is expressive, we think less about what's happening inside functions and focus more on relations between function inputs and their outputs.

• Pure functions have a unique mappings from input to output
• Running pure functions inline is representative of a unique value
• Pure functions calling other pure functions won't complicate our mental model

How to Identify and Encapsulate Impurities within Our Programs Every program has impure functions; they are the only ticket in town for reading, writing and displaying information. In order to protect the benefits, we've gained by writing pure functions; we'll begin looking at how we can isolate impure code while still using it to feed us information.

• Identify which parts of our program is pure and which are impure
• Pure functions can return impure functions without breaking referential transparency
• We can defer impure operations and pass results into pure functions as dependencies

How to Identify and Encapsulate Impurities within Our Programs Every program has impure functions; they are the only ticket in town for reading, writing and displaying information. In order to protect the benefits, we've gained by writing pure functions; we'll begin looking at how we can isolate impure code while still using it to feed us information.

• Identify which parts of our program is pure and which are impure
• Pure functions can return impure functions without breaking referential transparency
• We can defer impure operations and pass results into pure functions as dependencies

How to Identify and Encapsulate Impurities within Our Programs Every program has impure functions; they are the only ticket in town for reading, writing and displaying information. In order to protect the benefits, we've gained by writing pure functions; we'll begin looking at how we can isolate impure code while still using it to feed us information.

• Identify which parts of our program is pure and which are impure
• Pure functions can return impure functions without breaking referential transparency
• We can defer impure operations and pass results into pure functions as dependencies

How to Identify and Encapsulate Impurities within Our Programs Every program has impure functions; they are the only ticket in town for reading, writing and displaying information. In order to protect the benefits, we've gained by writing pure functions; we'll begin looking at how we can isolate impure code while still using it to feed us information.

• Identify which parts of our program is pure and which are impure
• Pure functions can return impure functions without breaking referential transparency
• We can defer impure operations and pass results into pure functions as dependencies

Every program has impure functions; they are the only ticket in town for reading, writing and displaying information. In order to protect the benefits, we've gained by writing pure functions; we'll begin looking at how we can isolate impure code while still using it to feed us information.

• Identify which parts of our program is pure and which are impure
• Pure functions can return impure functions without breaking referential transparency
• We can defer impure operations and pass results into pure functions as dependencies

Every program has impure functions; they are the only ticket in town for reading, writing and displaying information. In order to protect the benefits, we've gained by writing pure functions; we'll begin looking at how we can isolate impure code while still using it to feed us information.

• Identify which parts of our program is pure and which are impure
• Pure functions can return impure functions without breaking referential transparency
• We can defer impure operations and pass results into pure functions as dependencies

Abstracting Language Constructs with Higher-Order Functions. 5 lectures 01:07:15 Promoting Reusability with Higher-Order Functions Pure functions seem to restrict what we’re able to do in our apps, higher-order functions open our eyes to new ways we can write and use functions. They give us powerful tools and reusable utilities.

• Accepting functions as input creates flexible and generic utilities
• Returning a function to create a reusable utility
• Use higher-order functions to configure objects with lots of setup

Replacing Loops with Higher-Order Functions There are constructs in our programs we have grown accustom to always using, loops are one of these constructs. We can stop writing loops and instead use higher-order functions. This will make our code more readable, expressive and open our thinking to new ways of using higher-order functions.

• Look at imperative loops, identify the parts that change.
• A wrapped function can pass values in as arguments
• Create higher-order utilities that will work over any array

A Better Way to Map and Filter JavaScript added the higher-order map and filter methods to Arrays in ES5.1 but they don’t work in the way we as functional programmers need. We can make our own implementations that will certainly prove to be more and more useful the further we get into functional programming.

• Visualize the way map and filter work over a collection
• Create higher-order function implementations of map and filter
• Decouple the work and load from our higher-order functions

Reasoning with Reduce Reduce is another very popular higher-order function used for working over collections of data. It can be a little more difficult to reason about than map and filter, however it can have a lot more uses than map and filter as well...