countries.json = a geojson with data from Natural Earth

generate-bbox.js

'use strict';

const turf = require('turf');
const countries = require('./countries.json')

let bboxs = countries.features.map(function(feature) {
  if (feature.properties.ISO_A2 !== '-99') {
    return {
      iso: feature.properties.ISO_A2,
      name: feature.properties.ADMIN,
      bbox: turf.bbox(feature)
    }
  }
})

console.log(bboxs)