webpack/hot/only-dev-server.js

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

if(module.hot) {
	var lastData;
	function upToDate() {
		return lastData.indexOf(__webpack_hash__) >= 0;
	}
	function check() {
		module.hot.check(function(err, updatedModules) {
			if(err) {
				if(module.hot.status() in {abort:1,fail:1}) {
					console.warn("[HMR] Cannot check for update. Need to do a full reload!");
				} else {
					console.warn("[HMR] Update check failed: " + err);
				}
				return;
			}

			if(!updatedModules)
				return console.log("[HMR] No Update found.");

			module.hot.apply({
				ignoreUnaccepted: true
			}, function(err, renewedModules) {
				if(err) {
					if(module.hot.status() in {abort:1,fail:1}) {
						console.warn("[HMR] Cannot apply update (Need to do a full reload!): " + err);
					} else {
						console.warn("[HMR] Update failed: " + err);
					}
					return;
				}

				if(!upToDate()) {
					check();
				}

				var unacceptedModules = updatedModules.filter(function(moduleId) {
					return renewedModules.indexOf(moduleId) < 0;
				});

				if(unacceptedModules.length > 0) {
					console.warn("[HMR] The following modules couldn't be hot updated: (They would need a full reload!)");
					unacceptedModules.forEach(function(moduleId) {
						console.warn("[HMR]  - " + moduleId);
					});
				}

				if(!renewedModules || renewedModules.length === 0) {
					console.log("[HMR] Nothing hot updated.");
				} else {
					console.log("[HMR] Updated modules:");
					renewedModules.forEach(function(moduleId) {
						console.log("[HMR]  - " + moduleId);
					});
				}
				if(upToDate()) {
					console.log("[HMR] App is up to date.");
				}


			});
		});
	}
	window.onmessage = function(event) {
		if(typeof event.data === "string" && event.data.indexOf("webpackHotUpdate") === 0) {
			lastData = event.data;
			if(!upToDate() && module.hot.status() === "idle") {
				console.log("[HMR] Checking for updates on the server...");
				check();
			}
		}
	};
	console.log("[HMR] Waiting for update signal from WDS...");
} else {
	throw new Error("[HMR] Hot Module Replacement is disabled");
}