packages/node_modules/pouchdb-adapter-leveldb/src/index.js

import CoreLevelPouch from 'pouchdb-adapter-leveldb-core';
import { jsExtend as extend } from 'pouchdb-utils';
import requireLeveldown from './requireLeveldown';
import migrate from './migrate';

function LevelDownPouch(opts, callback) {

  // Users can pass in their own leveldown alternative here, in which case
  // it overrides the default one. (This is in addition to the custom builds.)
  var leveldown = opts.db;

  /* istanbul ignore else */
  if (!leveldown) {
    leveldown = requireLeveldown();

    /* istanbul ignore if */
    if (leveldown instanceof Error) {
      return callback(leveldown);
    }
  }

  var _opts = extend({
    db: leveldown,
    migrate: migrate
  }, opts);

  CoreLevelPouch.call(this, _opts, callback);
}

// overrides for normal LevelDB behavior on Node
LevelDownPouch.valid = function () {
  return true;
};
LevelDownPouch.use_prefix = false;

export default function (PouchDB) {
  PouchDB.adapter('leveldb', LevelDownPouch, true);
}