ethers.js/packages/providers/src.ts/tests/create-provider.ts

import {
    AlchemyProvider,
    AnkrProvider,
    CloudflareProvider,
    EtherscanProvider,
    InfuraProvider,
    PocketProvider,

    FallbackProvider,
} from "../index.js";

import type { AbstractProvider } from "../index.js";

interface ProviderCreator {
    name: string;
    networks: Array<string>;
    create: (network: string) => null | AbstractProvider;
};

const allNetworks = [ "default", "homestead" ];

const ProviderCreators: Array<ProviderCreator> = [
    {
        name: "AlchemyProvider",
        networks: allNetworks,
        create: function(network: string) {
            return new AlchemyProvider(network, "YrPw6SWb20vJDRFkhWq8aKnTQ8JRNRHM");
        }
    },
    {
        name: "AnkrProvider",
        networks: [ "homestead", "matic", "arbitrum" ],
        create: function(network: string) {
            return new AnkrProvider(network);
        }
    },
    {
        name: "CloudflareProvider",
        networks: [ "default", "homestead" ],
        create: function(network: string) {
            return new CloudflareProvider(network);
        }
    },
    {
        name: "EtherscanProvider",
        networks: allNetworks,
        create: function(network: string) {
            return new EtherscanProvider(network, "FPFGK6JSW2UHJJ2666FG93KP7WC999MNW7");
        }
    },
    {
        name: "InfuraProvider",
        networks: allNetworks,
        create: function(network: string) {
            return new InfuraProvider(network, "49a0efa3aaee4fd99797bfa94d8ce2f1");
        }
    },
    {
        name: "PocketProvider",
        networks: allNetworks,
        create: function(network: string) {
            const apiKeys: Record<string, string> = {
                homestead: "6004bcd10040261633ade990",
                ropsten: "6004bd4d0040261633ade991",
                rinkeby: "6004bda20040261633ade994",
                goerli: "6004bd860040261633ade992",
            };
            return new PocketProvider(network, apiKeys[network]);
        }
    },

    {
        name: "FallbackProvider",
        networks: allNetworks,
        create: function(network: string) {
            const providers: Array<AbstractProvider> = [];
            for (const creator of ProviderCreators) {
                if (creator.name === "FallbackProvider") { continue; }
                if (creator.networks.indexOf(network) >= 0) {
                    const provider = creator.create(network);
                    if (provider) { providers.push(provider); }
                }
            }
            return new FallbackProvider(providers);
        }
    },
];

export const providerNames = Object.freeze(ProviderCreators.map((c) => (c.name)));

function getCreator(provider: string): null | ProviderCreator {
    const creators = ProviderCreators.filter((c) => (c.name === provider));
    if (creators.length === 1) { return creators[0]; }
    return null;
}

export function getProviderNetworks(provider: string): Array<string> {
    const creator = getCreator(provider);
    if (creator) { return creator.networks; }
    return [ ];
}

export function getProvider(provider: string, network: string): null | AbstractProvider {
    const creator = getCreator(provider);
    if (creator) { return creator.create(network); }
    return null;
}

export function connect(network: string): AbstractProvider {
    const provider = getProvider("InfuraProvider", network);
    if (provider == null) { throw new Error(`could not connect to ${ network }`); }
    return provider;
}