webpack/hot/signal.js

Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.

/*
	MIT License http://www.opensource.org/licenses/mit-license.php
	Author Tobias Koppers @sokra
*/
/*globals __resourceQuery */
if (module.hot) {
	var log = require("./log");

	/**
	 * @param {boolean=} fromUpdate true when called from update
	 */
	var checkForUpdate = function checkForUpdate(fromUpdate) {
		module.hot
			.check()
			.then(function (updatedModules) {
				if (!updatedModules) {
					if (fromUpdate) log("info", "[HMR] Update applied.");
					else log("warning", "[HMR] Cannot find update.");
					return;
				}

				return module.hot
					.apply({
						ignoreUnaccepted: true,
						onUnaccepted: function (data) {
							log(
								"warning",
								"Ignored an update to unaccepted module " +
									data.chain.join(" -> ")
							);
						}
					})
					.then(function (renewedModules) {
						require("./log-apply-result")(updatedModules, renewedModules);

						checkForUpdate(true);
						return null;
					});
			})
			.catch(function (err) {
				var status = module.hot.status();
				if (["abort", "fail"].indexOf(status) >= 0) {
					log("warning", "[HMR] Cannot apply update.");
					log("warning", "[HMR] " + log.formatError(err));
					log("warning", "[HMR] You need to restart the application!");
				} else {
					log("warning", "[HMR] Update failed: " + (err.stack || err.message));
				}
			});
	};

	process.on(__resourceQuery.slice(1) || "SIGUSR2", function () {
		if (module.hot.status() !== "idle") {
			log(
				"warning",
				"[HMR] Got signal but currently in " + module.hot.status() + " state."
			);
			log("warning", "[HMR] Need to be in idle state to start hot update.");
			return;
		}

		checkForUpdate();
	});
} else {
	throw new Error("[HMR] Hot Module Replacement is disabled.");
}