Get all the pokemons from the PokeAPI and save it to a JSON file

package.json

{
  "name": "saveAllPokemons",
  "version": "0.0.1",
  "main": "saveAllPokemons.js",
  "scripts": {
    "start": "node saveAllPokemons.js"
  },
  "dependencies": {
    "axios": "^0.19.0"
  },
  "license": "MIT"
}

saveAllPokemons.js

const {get} = require("axios");
const fs = require("fs");

(async () => {
  try {
    const pokemons = await getAllPokemons();
    fs.writeFile('pokemons.json', JSON.stringify(pokemons, null, 2), (err) => {
      if (err) throw err;
      console.log('The pokemons have been saved!');
    });
  } catch (e) {
    console.error('Error getting pokemons', e.toString())
  }
})();

const getAllPokemons = async () => await processPage();

const processPage = (url = "https://pokeapi.co/api/v2/pokemon", cache = []) => new Promise((res, rej) => {
  if (!!url) {
    get(url)
      .then(({data}) => {
      if (data.next) {
        console.log('Processing...', cache.length, 'processed.')
        res(processPage(data.next, cache.concat(data.results.map(parsePokemon))));
      } else {
        res(cache.concat(data.results.map(parsePokemon)))
      }
    }).catch(e => {
      console.error('Error getting page', e.toString());
      rej(e)
    })}
  else {
    return res(cache)
  }
});

const parsePokemon = ({name, url}) => {
  const [, id] = url.split('/').reverse();
  return {
    name: capitalize(name),
    url,
    id,
    img: `https://raw.githubusercontent.com/PokeAPI/sprites/master/sprites/pokemon/${id}.png`
  }
};

const capitalize = s => s.charAt(0).toUpperCase() + s.substring(1).toLowerCase();