https://socket.io/assets/js/7dc64930.6ae48be4.js

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middleware"}},c=[],s={toc:c},m="wrapper";function p(e){let{components:t,...n}=e;return(0,r.kt)(m,(0,a.Z)({},s,n,{components:t,mdxType:"MDXLayout"}),(0,r.kt)("h1",{id:"how-to-register-a-global-middleware"},"How to register a global middleware"),(0,r.kt)("p",null,"In Socket.IO v2, a middleware that was registered for the main namespace would act as a global middleware, applying to all namespaces, since a client would first connect to the main namespace, and then to the custom namespace:"),(0,r.kt)("pre",null,(0,r.kt)("code",{parentName:"pre",className:"language-js"},'// Socket.IO v2\n\nio.use((socket, next) => {\n  // always triggered, even if the client tries to reach the custom namespace\n  next();\n});\n\nio.of("/my-custom-namespace").use((socket, next) => {\n  // triggered after the global middleware\n  next();\n});\n')),(0,r.kt)("p",null,"This is not the case any more starting with Socket.IO v3: a middleware attached to the main namespace is only called when a client tries to reach 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1\n\nio.on("new_namespace", (namespace) => {\n  namespace.use(myGlobalMiddleware);\n});\n\n// and then declare the namespaces\nio.of("/my-custom-namespace");\n')),(0,r.kt)("admonition",{type:"caution"},(0,r.kt)("p",{parentName:"admonition"},"The namespaces that are registered before the ",(0,r.kt)("inlineCode",{parentName:"p"},"new_namespace")," listener won't be affected.")),(0,r.kt)("ul",null,(0,r.kt)("li",{parentName:"ul"},"or, when using ",(0,r.kt)("a",{parentName:"li",href:"/docs/v4/namespaces/#dynamic-namespaces"},"dynamic namespaces"),", by registering a middleware on the parent namespace:")),(0,r.kt)("pre",null,(0,r.kt)("code",{parentName:"pre",className:"language-js"},"const myGlobalMiddleware = (socket, next) => {\n  next();\n}\n\nio.use(myGlobalMiddleware);\n\nconst parentNamespace = io.of(/^\\/dynamic-\\d+$/);\n\nparentNamespace.use(myGlobalMiddleware);\n")),(0,r.kt)("admonition",{type:"caution"},(0,r.kt)("p",{parentName:"admonition"},"Existing namespaces always have priority over dynamic namespaces. For example:"),(0,r.kt)("pre",{parentName:"admonition"},(0,r.kt)("code",{parentName:"pre",className:"language-js"},'io.of("/admin");\n\nio.of(/.*/).use((socket, next) => {\n  // won\'t be called for the main namespace nor for the "/admin" namespace\n  next();\n});\n'))),(0,r.kt)("p",null,"Related:"),(0,r.kt)("ul",null,(0,r.kt)("li",{parentName:"ul"},(0,r.kt)("a",{parentName:"li",href:"/docs/v4/middlewares/"},"Middleware documentation")),(0,r.kt)("li",{parentName:"ul"},(0,r.kt)("a",{parentName:"li",href:"/docs/v4/migrating-from-2-x-to-3-0/#no-more-implicit-connection-to-the-default-namespace"},"v2 to v3 migration"))))}p.isMDXComponent=!0}}]);