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midudev/using_map_and_filter.js

Created October 7, 2016 17:47
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Example about how to use reduce to map and filter an array with one iteration
Raw
using_map_and_filter.js
const MULTIMEDIA_IMAGE_TYPE_ID = 12
const multimedias = [
{ mediumSizeUrl: 'dog.jpg', typeId: 2 },
{ mediumSizeUrl: 'panda.jpg', typeId: 12 },
{ mediumSizeUrl: 'koala.jpg', typeId: 12 },
{ mediumSizeUrl: 'trex.jpg', typeId: 5 },
{ mediumSizeUrl: 'ratilla.jpg', typeId: 12 }
];
const isUsable = media => media.typeId === MULTIMEDIA_IMAGE_TYPE_ID && media.mediumSizeUrl;
const images = multimedias.filter(isUsable).map(media => media.mediumSizeUrl)
console.log(images) // ["panda.jpg", "koala.jpg", "ratilla.jpg"]
Raw
using_reduce.js
const MULTIMEDIA_IMAGE_TYPE_ID = 12
const multimedias = [
{ mediumSizeUrl: 'dog.jpg', typeId: 2 },
{ mediumSizeUrl: 'panda.jpg', typeId: 12 },
{ mediumSizeUrl: 'koala.jpg', typeId: 12 },
{ mediumSizeUrl: 'trex.jpg', typeId: 5 },
{ mediumSizeUrl: 'ratilla.jpg', typeId: 12 }
];
const isUsable = media => media.typeId === MULTIMEDIA_IMAGE_TYPE_ID && media.mediumSizeUrl;
const images = multimedias.reduce((accumulator, media) => {
if (isUsable(media)) accumulator.push(media.mediumSizeUrl)
return accumulator;
}, [])
console.log(images) // ["panda.jpg", "koala.jpg", "ratilla.jpg"]
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