Evolution Client

Covers the PokéAPI's evolution section: evolution chains, the triggers that advance them, and the hidden values some evolutions are decided by.

import { EvolutionClient } from 'pokenode-ts';

const api = new EvolutionClient();

const chain = await api.getEvolutionChainById(1);

console.log(chain.chain.species.name); // "bulbasaur"
console.log(chain.chain.evolves_to[0].species.name); // "ivysaur"

Methods

Evolution chains

Method	Returns
getEvolutionChainById(id)	EvolutionChain
listEvolutionChains(offset?, limit?)	APIResourceList

Evolution triggers

Method	Returns
getEvolutionTriggerByName(name)	EvolutionTrigger
getEvolutionTriggerById(id)	EvolutionTrigger
listEvolutionTriggers(offset?, limit?)	NamedAPIResourceList

Evolution variables

Method	Returns
getEvolutionVariableByName(name)	EvolutionVariable
getEvolutionVariableById(id)	EvolutionVariable
listEvolutionVariables(offset?, limit?)	NamedAPIResourceList

An EvolutionVariable — the encryption constant, the personality value, the direction and length of Milcery's spin — is what an EvolutionDetail.condition_expression reads. Its source says whether the value is stored on the Pokémon (pokemon) or supplied by the player (player-input). See hidden values.

INFO

Evolution chains have no names upstream, so there is no getEvolutionChainByName. To go from a Pokémon to its chain, read evolution_chain.url off its species and follow it — see below.

Walking a chain

EvolutionChain.chain is a recursive ChainLink: each link carries the species at that stage and an evolves_to array of the links after it. Branching evolutions — Eevee — are why it is an array rather than a single value.

import { EvolutionClient, type ChainLink } from 'pokenode-ts';

const names = (link: ChainLink): string[] => [
  link.species.name,
  ...link.evolves_to.flatMap(names),
];

const chain = await new EvolutionClient().getEvolutionChainById(67);

console.log(names(chain.chain)); // eevee and every evolution it branches into

From a Pokémon to its chain

The chain id is not the Pokémon id. Go through the species:

import { PokemonClient, EvolutionClient, UtilityClient, type EvolutionChain } from 'pokenode-ts';

const species = await new PokemonClient().getPokemonSpeciesByName('eevee');

// The species carries a URL rather than an id, so follow it directly.
const chain = await new UtilityClient().getResourceByUrl<EvolutionChain>(
  species.evolution_chain.url,
);

Using constants

import { EvolutionClient, EVOLUTION_TRIGGERS, EVOLUTION_VARIABLES } from 'pokenode-ts';

const api = new EvolutionClient();

const levelUp = await api.getEvolutionTriggerById(EVOLUTION_TRIGGERS.LEVEL_UP);
const ec = await api.getEvolutionVariableById(EVOLUTION_VARIABLES.ENCRYPTION_CONSTANT);