#LWSContext

A wrapper around struct lws_context. The context owns the default vhost, the listener (if any), the protocol callback table, and any mounts. Implemented in lws-context.c.

#Construction

const ctx = new LWSContext(info);

createServer(info) (exported from 'lws') is a thin alias for the same constructor call — JS_CallConstructor on LWSContext under the hood — meant for call sites where info.port is set, i.e. the context will listen. It's purely a naming convenience; the two are otherwise identical, and either is fine for a client-only context too.

info is a plain object mapped to struct lws_context_creation_info. Properties whose JS name is camelCase are also accepted in their underscore form (e.g. vhostName or vhost_name), thanks to the camelize lookup in js-utils.c.

Whenever a property is not provided and port is missing, the context is created with port = CONTEXT_PORT_NO_LISTEN (no listener — suitable for pure clients).

#Common properties

#TLS properties

Built only when libwebsockets is compiled with LWS_WITH_TLS. Each of serverSsl* / clientSsl* may be either a file path string (*_filepath) or an ArrayBuffer containing the certificate or key material (*_mem / *_mem_len set accordingly). The str_or_buf_property() helper picks the right field automatically:

#SOCKS5

Built only with LWS_WITH_SOCKS5:

#WebSocket extensions

#Instance methods

#clientConnect

Two call styles:

ctx.clientConnect('https://example.com/path');
ctx.clientConnect('wss://example.com/ws', { protocol: 'chat' });
ctx.clientConnect({
  address: 'example.com',
  port: 443,
  path: '/foo',
  ssl: true,
  protocol: 'http',
});

Recognised properties on the info object:

When a URI string is passed, the scheme decides: http* → method = 'GET'; https/wss → ssl_connection is set to a permissive default (`USE_SSL | ALLOW_SELFSIGNED | ALLOW_EXPIRED | SKIP_SERVER_CERT_HOSTNAME_CHECK | ALLOW_INSECURE`).

Returns the freshly created LWSSocket. Even on failure the socket object exists; you observe failures via the protocol's onClientConnectionError callback.

#createUdp

UDP is connectionless, so both "bind a listening socket that receives datagrams from any peer" and "create a socket pre-connected to one fixed remote peer" go through this single entry point, distinguished by whether address is given / bind is set:

const listener = ctx.createUdp({ protocol: 'udp-echo', bind: true, port: 9002 });
const client = ctx.createUdp({ protocol: 'udp-echo', address: '127.0.0.1', port: 9002 });

Recognised properties on the options object:

A single UDP wsi, unlike TCP, never gets one child wsi per peer — see onRawRx's extra LWSSockAddr46 argument (callbacks.md) for how a listener tells its many peers apart, and wsi.write(data, sockaddr) (see LWSSocket.md) for targeting a reply back at one of them.

Throws TypeError if protocol is missing, InternalError if the named vhost doesn't exist or lws_create_adopt_udp() fails.

#Instance accessors (read-only)

The info property is also set during construction — it's the original options object, kept alive for the lifetime of the context (JS_PROP_CONFIGURABLE).

#Lifecycle

• The context is finalised when the JS object is garbage collected, which triggers lws_context_destroy() automatically.
• destroy() is safe to call early; subsequent method calls throw InternalError("LWSContext internal lws_context has been destroyed").
• The constructor may trigger callbacks before returning, because lws_create_context() is the last step performed.