process.dlopen

process.dlopen(module, filename, flags?): void

The process.dlopen() method allows dynamically loading shared objects. It is primarily used by require() to load C++ Addons, and should not be used directly, except in special cases. In other words, require() should be preferred over process.dlopen() unless there are specific reasons such as custom dlopen flags or loading from ES modules.

The flags argument is an integer that allows to specify dlopen behavior. See the os.constants.dlopen documentation for details.

An important requirement when calling process.dlopen() is that the module instance must be passed. Functions exported by the C++ Addon are then accessible via module.exports.

The example below shows how to load a C++ Addon, named local.node, that exports a foo function. All the symbols are loaded before the call returns, by passing the RTLD_NOW constant. In this example the constant is assumed to be available.

import { dlopen } from 'node:process';
import { constants } from 'node:os';
import { fileURLToPath } from 'node:url';

const module = { exports: {} };
dlopen(module, fileURLToPath(new URL('local.node', import.meta.url)),
       constants.dlopen.RTLD_NOW);
module.exports.foo();

const { dlopen } = require('node:process');
const { constants } = require('node:os');
const { join } = require('node:path');

const module = { exports: {} };
dlopen(module, join(__dirname, 'local.node'), constants.dlopen.RTLD_NOW);
module.exports.foo();