Projection/JavaScript/4-imperative.js at master · HowProgrammingWorks/Projection · GitHub

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'use strict';

// Projection

const projection = (meta) => {

const keys = Object.keys(meta);

return (obj) => {

const hash = {};

keys.forEach((key) => {

const def = meta[key];

const [field, fn] = def;

const val = obj[field];

hash[key] = fn ? fn(val) : val;

});

return hash;

};

// Dataset

const persons = [

{ name: 'Marcus Aurelius', city: 'Rome', born: 121 },

{ name: 'Victor Glushkov', city: 'Rostov on Don', born: 1923 },

{ name: 'Ibn Arabi', city: 'Murcia', born: 1165 },

{ name: 'Mao Zedong', city: 'Shaoshan', born: 1893 },

{ name: 'Rene Descartes', city: 'La Haye en Touraine', born: 1596 },

];

// Metadata

const md = {

name: ['name'],

place: ['city', (s) => `<${s.toUpperCase()}>`],

age: ['born', (year) => (

new Date().getFullYear() -

new Date(year.toString()).getFullYear()

)]

};

// Usage

const p1 = projection(md);

const data = persons.map(p1);

console.dir(data);

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