source: imaps-frontend/node_modules/webpack/hot/signal.js

/*
        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.");
}