minimize.js

var fs = require('fs');
var plants = JSON.parse(fs.readFileSync('./plants.geojson'));

var output = {
    type: 'FeatureCollection',
    features: plants.features.map(feature => {
        return {
            type: 'Feature',
            geometry: feature.geometry,
            properties: {
                n: feature.properties.Plant_Name,
                t: feature.properties.Total_MW,
                c: feature.properties.Coal_MW,
                ng: feature.properties.NG_MW,
                h: feature.properties.Hydro_MW,
                s: feature.properties.Solar_MW,
                w: feature.properties.Wind_MW
            }
        }
    })
};

fs.writeFileSync('./plants.min.json', JSON.stringify(output));