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pyykkis/app.coffee

Last active December 20, 2015 02:09
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Calculate sum of variable amount of values
Raw
app.coffee
reduce = (f, initial) -> (xs) -> Array::reduce.call xs, f, initial
butlast = (xs) -> xs.slice 0, xs.length - 1
sum = (x, y) -> x + y
addInputStream = (xs) ->
input = $('<input />')
.appendTo('#inputs')
.asEventStream('input')
.map('.target.value')
.map(parseInt)
.toProperty(0)
xs.concat [input]
removeInputStream = (xs) ->
$('input').last().remove()
butlast xs
$ ->
addInput = $('#add-input').asEventStream 'click', -> addInputStream
removeInput = $('#remove-input').asEventStream 'click', -> removeInputStream
inputs = addInput.merge(removeInput).scan [], (xs, f) -> f xs
values = inputs.flatMap Bacon.combineAsArray
sum = values.map(reduce sum, 0)
sum.assign $('#result'), 'text'
Raw
index.html
<html>
<head>
</head>
<body>
<button id="add-input">Add input</button>
<button id="remove-input">Remove input</button>
<div id="inputs"></div>
<div id="result"></div>
<script src="bower_components/jquery/jquery.js"></script>
<script src="bower_components/bacon/dist/Bacon.js"></script>
<script src="app.js"></script>
</body>
</html>
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