hyperscript.org/dist/socket.js

a small scripting language for the web

(function (self, factory) {
	const plugin = factory(self)

	if (typeof exports === 'object' && typeof exports['nodeName'] !== 'string') {
		module.exports = plugin
	} else {
		if ('_hyperscript' in self) self._hyperscript.use(plugin)
	}
})(typeof self !== 'undefined' ? self : this, self => {

	function genUUID() {
		return "xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx".replace(/[xy]/g, function (c) {
			var r = (Math.random() * 16) | 0,
				v = c == "x" ? r : (r & 0x3) | 0x8;
			return v.toString(16);
		});
	}

	function parseUrl(url) {
		var finalUrl = url;
		if (finalUrl.indexOf("/") === 0) {  // complete absolute paths without scheme only
			var basePart = window.location.hostname + (window.location.port ? ':' + window.location.port : '');
			if (window.location.protocol === 'https:') {
				finalUrl = "wss://" + basePart + finalUrl;
			} else if (window.location.protocol === 'http:') {
				finalUrl = "ws://" + basePart + finalUrl;
			}
		}
		return finalUrl;
	}

	function createSocket(url) {
		var parsedUrl = parseUrl(url.evaluate());
		return new WebSocket(parsedUrl);
	}

	/**
	 * @param {HyperscriptObject} _hyperscript
	 */
	return _hyperscript => {

		/** @type {(string | symbol)[]} */
		var PROXY_BLACKLIST = ["then", "catch", "length", "asyncWrapper", "toJSON"];

		_hyperscript.addFeature("socket", function (parser, runtime, tokens) {
			function getProxy(timeout) {
				return new Proxy(
					{},
					{
						get: function (obj, property) {
							if (PROXY_BLACKLIST.indexOf(property) >= 0) {
								return null;
							} else if (property === "noTimeout") {
								return getProxy(-1);
							} else if (property === "timeout") {
								return function (i) {
									return getProxy(parseInt(i));
								};
							} else {
								return function () {
									var uuid = genUUID();
									var args = [];
									for (var i = 0; i < arguments.length; i++) {
										args.push(arguments[i]);
									}
									var rpcInfo = {
										iid: uuid,
										function: property,
										args: args,
									};
									socket = socket ? socket : createSocket(url); //recreate socket if needed
									socket.send(JSON.stringify(rpcInfo));

									var promise = new Promise(function (resolve, reject) {
										promises[uuid] = {
											resolve: resolve,
											reject: reject,
										};
									});

									if (timeout >= 0) {
										setTimeout(function () {
											if (promises[uuid]) {
												promises[uuid].reject("Timed out");
											}
											delete promises[uuid];
										}, timeout); // TODO configurable?
									}
									return promise;
								};
							}
						},
					}
				);
			}

			if (tokens.matchToken("socket")) {
				var name = parser.requireElement("dotOrColonPath", tokens);
				var qualifiedName = name.evaluate();
				var nameSpace = qualifiedName.split(".");
				var socketName = nameSpace.pop();

				var promises = {};
				var url = parser.requireElement("stringLike", tokens);

				var defaultTimeout = 10000;
				if (tokens.matchToken("with")) {
					tokens.requireToken("timeout");
					defaultTimeout = parser.requireElement("expression", tokens).evaluate();
				}

				if (tokens.matchToken("on")) {
					tokens.requireToken("message");
					if (tokens.matchToken("as")) {
						tokens.requireToken("json");
						var jsonMessages = true;
					}
					var messageHandler = parser.requireElement("commandList", tokens);
					var implicitReturn = {
						type: "implicitReturn",
						op: function (context) {
							return runtime.HALT;
						},
						execute: function (context) {
							// do nothing
						},
					};
					var end = messageHandler;
					while (end.next) {
						end = end.next;
					}
					end.next = implicitReturn;
					// TODO set parent?
					// parser.setParent(implicitReturn, initFeature);
				}

				var socket = createSocket(url);
				var rpcProxy = getProxy(defaultTimeout);

				var socketObject = {
					raw: socket,
					dispatchEvent: function (evt) {
						var details = evt.detail;
						// remove hyperscript internals
						delete details.sender;
						delete details._namedArgList_;
						socket.send(JSON.stringify(Object.assign({ type: evt.type }, details)));
					},
					rpc: rpcProxy,
				};

				var socketFeature = {
					name: socketName,
					socket: socketObject,
					install: function (target) {
						runtime.assignToNamespace(target, nameSpace, socketName, socketObject);
					},
				};

				socket.onmessage = function (evt) {
					var data = evt.data;
					try {
						var dataAsJson = JSON.parse(data);
					} catch (e) {
						// not JSON
					}

					// RPC reply
					if (dataAsJson && dataAsJson.iid) {
						if (dataAsJson.throw) {
							promises[dataAsJson.iid].reject(dataAsJson.throw);
						} else {
							promises[dataAsJson.iid].resolve(dataAsJson.return);
						}
						delete promises[dataAsJson.iid];
					}

					if (messageHandler) {
						var context = runtime.makeContext(socketObject, socketFeature, socketObject);
						if (jsonMessages) {
							if (dataAsJson) {
								context.locals.message = dataAsJson;
								context.result = dataAsJson;
							} else {
								throw "Received non-JSON message from socket: " + data;
							}
						} else {
							context.locals.message = data;
							context.result = data;
						}
						messageHandler.execute(context);
					}
				};

				// clear socket on close to be recreated
				socket.addEventListener("close", function (e) {
					socket = null;
				});

				return socketFeature;
			}
		});
	}
})