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Main examples from Martin Fowler article on Collection Pipeline programming pattern with javascript and underscore.js
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'use strict'; | |
/** | |
* Implementing main examples from Martin Fowler article | |
* on Collection Pipeline programming pattern: | |
* http://martinfowler.com/articles/collection-pipeline/ | |
* with #javascript and underscore.js: http://underscorejs.org/ | |
* | |
* tested with nodejs v0.10.32 | |
* | |
* underscore.js is required: | |
* $npm install underscore | |
*/ | |
var _ = require('underscore'); | |
var articles = [ | |
{title: 'NoDBA', | |
words: 561, | |
tags: ['nosql', 'people', 'orm'], | |
type: ':bliki'}, | |
{title: 'Infodeck', | |
words: 1145, | |
tags: ['nosql', 'writing'], | |
type: ':bliki'}, | |
{title: 'OrmHate', | |
words: 1718, | |
tags: ['nosql', 'orm'], | |
type: ':bliki'}, | |
{title: 'ruby', | |
words: 1313, | |
tags: ['ruby'], | |
type: ':article'}, | |
{title: 'DDD_Aggregate', | |
words: 482, | |
tags: ['nosql', 'ddd'], | |
type: ':bliki'}]; | |
// count words _ | |
var result = _.chain(articles).map('words').reduce(function(w, a){return w+a}).value(); | |
console.log('wordcount: ', result); | |
// count articles by type (as in Fowler's article) | |
result = _.chain(articles) | |
.groupBy('type') | |
.map(function(value, key) {return [key, value.length];}) | |
.object() | |
.value(); | |
console.log('articles by type (original): ', result); | |
// count articles by type (using Underscore's countBy function) | |
result = _(articles).countBy('type'); | |
console.log('articles by type (_.countBy): ', result); | |
// count number of articles for each tag | |
result = _.chain(articles) | |
.map(function(article){return _(article.tags).map(function(tag){return [tag, article];})}) | |
.flatten(true) | |
.reduce(function(o, a){o[a[0]] ? o[a[0]].push(a[1]) : o[a[0]] = [a[1]]; return o;}, {}) | |
.map(function(articleList,tag){return [tag, {'articles': articleList.length, 'words': _.reduce(articleList, function(w, a){return w + a.words}, 0)}];}) | |
.object() | |
.value(); | |
console.log('articles for each tag:', result); |
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