Automagical pivot table for unwieldy sheets

csv.catalog.js

/*

Automagical Pivot "Table"
1. Export your unwieldy xls into csv
2. Paste csv into ES6 as example below
3. Inspect the JS object returned

*/

Example:
csv(`Name,ID,Category,USD
Alpha,123,Sales,"123,456"
Romeo,456,Sales,"123,456,789"`)
// NOTE
// 1. Backticks allow you to paste with quotes and newlines right away


// "Includes" (2 hoisted dependencies)
/* 
┌─┐┌─┐┬  ┬
│  └─┐└┐┌┘
└─┘└─┘ └┘ w10 */
function csv(string){
    let [labels, ...data] = 
        string
    // 2. Only the "123,456,789" special case is handled
            .replace(/"[\d,]+"/g, n => n.replace(/[",]/g,''))
            .split('\n')
    // 3. YMMV; using naive CSV parsing for simplicity
            .map(text => text.split(','));
    return Catalog(...data.map(row => zip(labels, row)));

    function zip(labels, row){
        return labels.reduce((data, key, i) => 
            Object.assign(data, {[key]: row[i]})
        , {});
    }
}

/*
┌─┐┌─┐┌┬┐┌─┐┬  ┌─┐┌─┐
│  ├─┤ │ ├─┤│  │ ││ ┬
└─┘┴ ┴ ┴ ┴ ┴┴─┘└─┘└─┘ w10 */
function Catalog(...items){
    return items.reduce((catalog), {});

    function catalog(dict, item){
        for (let [key, value] of Object.entries(item)){
            let initial = key in dict? dict[key]: new Map;
            switch (value.constructor.name){
                case 'Array':
                    dict[key] = value.reduce(catalog, initial);
                    break;
                case 'Object':
                    dict[key] = [value].reduce(catalog, initial);
                    break;
                default:
                    dict[key] = archive(initial, value, item);
                    break;
            }
        }
        return dict;

        function archive(context, key, item){
            context[key] = key in context ?
                context[key].concat(item)
                : [item];
            return context;
        }
    }
}