Functional Reactive JavaScript

Slide 1

Slide 1 text

Functional   Reactive  JavaScript

Slide 2

Slide 2 text

Functional   Reactive  Programming

Slide 3

Slide 3 text

variable  snapshot of a value   at a specific time stream  all future values over time

Slide 4

Slide 4 text

Functional   Reactive  Programming

Slide 5

Slide 5 text

UI elements produce streams of values. Functions combine and transform those streams into new streams. Streams can be assigned to UI attributes   to effect UI output.

Slide 6

Slide 6 text

our approach   for this evening

Slide 7

Slide 7 text

–Johnny Appleseed “Type a quote here.”

Slide 8

Slide 8 text

for bonus points: TDD*! * Test-Driven Development

Slide 9

Slide 9 text

me me me Pete Hodgson Consultant at ThoughtWorks @ph1 blog.thepete.net

Slide 10

Slide 10 text

example #1. slider & label

Slide 11

Slide 11 text

slider

var wireUpSliderToLabel = function ( $slider, $label ){ var sliderValue = $slider.asEventStream('input', eventToVal); sliderValue.assign( $label, "text" ); }; ! var eventToVal = function(e){ return $(e.target).val(); };

Slide 12

Slide 12 text

slider

Slide 13

Slide 13 text

slider

Slide 14

Slide 14 text

slider

5 5 var wireUpSliderToLabel = function ( $slider, $label ){ var sliderValue = $slider.asEventStream('input', eventToVal); sliderValue.assign( $label, "text" ); }; ! var eventToVal = function(e){ return $(e.target).val(); };

Slide 15

Slide 15 text

slider

5 5 5 var wireUpSliderToLabel = function ( $slider, $label ){ var sliderValue = $slider.asEventStream('input', eventToVal); sliderValue.assign( $label, "text" ); }; ! var eventToVal = function(e){ return $(e.target).val(); };

Slide 16

Slide 16 text

5 5 5 2 var wireUpSliderToLabel = function ( $slider, $label ){ var sliderValue = $slider.asEventStream('input', eventToVal); sliderValue.assign( $label, "text" ); }; ! var eventToVal = function(e){ return $(e.target).val(); };

Slide 17

Slide 17 text

5 5 5 2 2 var wireUpSliderToLabel = function ( $slider, $label ){ var sliderValue = $slider.asEventStream('input', eventToVal); sliderValue.assign( $label, "text" ); }; ! var eventToVal = function(e){ return $(e.target).val(); };

Slide 18

Slide 18 text

epiphany declarative, not imperative

Slide 19

Slide 19 text

example #2. slider & label w. formatting

Slide 20

Slide 20 text

formatFn var wireUpSliderToFormattedLabel = function ( $slider, $label ){ var sliderValue = $slider.asEventStream('input', eventToVal); var formattedValue = sliderValue.map( ratioToPercentage ); formattedValue.assign( $label, "text" ); }; ! var ratioToPercentage = function(ratio){ return "" + Math.round(ratio*100) + "%"; } ! var eventToVal = function(e){ return $(e.target).val(); };

Slide 21

Slide 21 text

formatFn 0.05 var wireUpSliderToFormattedLabel = function ( $slider, $label ){ var sliderValue = $slider.asEventStream('input', eventToVal); var formattedValue = sliderValue.map( ratioToPercentage ); formattedValue.assign( $label, "text" ); }; ! var ratioToPercentage = function(ratio){ return "" + Math.round(ratio*100) + "%"; } ! var eventToVal = function(e){ return $(e.target).val(); };

Slide 22

Slide 22 text

“5%” formatFn 0.05 0.05 var wireUpSliderToFormattedLabel = function ( $slider, $label ){ var sliderValue = $slider.asEventStream('input', eventToVal); var formattedValue = sliderValue.map( ratioToPercentage ); formattedValue.assign( $label, "text" ); }; ! var ratioToPercentage = function(ratio){ return "" + Math.round(ratio*100) + "%"; } ! var eventToVal = function(e){ return $(e.target).val(); };

Slide 23

Slide 23 text

“5%” 5% formatFn 0.05 0.05 var wireUpSliderToFormattedLabel = function ( $slider, $label ){ var sliderValue = $slider.asEventStream('input', eventToVal); var formattedValue = sliderValue.map( ratioToPercentage ); formattedValue.assign( $label, "text" ); }; ! var ratioToPercentage = function(ratio){ return "" + Math.round(ratio*100) + "%"; } ! var eventToVal = function(e){ return $(e.target).val(); };

Slide 24

Slide 24 text

epiphany compose-ability (pipes & filters)

Slide 25

Slide 25 text

example #3. slider & grayscale swatch

Slide 26

Slide 26 text

example #4. sliders & color swatch

Slide 27

Slide 27 text

combineFn

Slide 28

Slide 28 text

combineFn 0.7 0.1 0.5

Slide 29

Slide 29 text

combineFn 0.7 0.1 0.5 { r: 0.7, g: 0.1, b: 0.5 }

Slide 30

Slide 30 text

combineFn 0.7 0.5 0.9 { r: 0.7, g: 0.1, b: 0.5 }

Slide 31

Slide 31 text

combineFn 0.7 0.5 0.9 { r: 0.7, g: 0.9, b: 0.5 }

Slide 32

Slide 32 text

epiphany most recent value is always available

Slide 33

Slide 33 text

epiphany very little need to manage mutable state

Slide 34

Slide 34 text

back to   theory

Slide 35

Slide 35 text

variable  snapshot of a value   at a specific time stream  all future values over time

Slide 36

Slide 36 text

var a = 12 var b = a + 10 // b == 22 a = 20 // b == 22

Slide 37

Slide 37 text

var a = 12 var b = a + 10 // b == 22 a = 20 // b == 22 var a = aStreamWith(12) var b = a.map( -> + 10 ) a.updateTo(20)

Slide 38

Slide 38 text

we’re just getting started

Slide 39

Slide 39 text

frp-talk-examples.thepete.net

Slide 40

Slide 40 text

thanks! questions?

Slide 41

Slide 41 text

@ph1 [email protected] frp-talk-examples.thepete.net blog.thepete.net slides.thepete.net