In a UIX app, UI is provided via default exports from the entrypoint.ts/entrypoint.tsx files located at the root of the backend or frontend directories.

There is a variety of values that can be exported from an entrypoint to be displayed in the browser client, including strings, HTML Elements, Blobs and more.

Example Entrypoints:

// backend/entrypoint.ts
export default "Hello, this is a simple text displayed on a website and loaded from the backend entrypoint"
// frontend/entrypoint.tsx
export default 

Entrypoint configurations

1. Just a frontend entrypoint

If there are no backend entrypoint exports, the UI is generated directly on each frontend client from the frontend entrypoint. This configuration is useful for complex web applications with user-specific UI and also when the UI content should not be available on the backend.

2. Just a backend entrypoint

UI generated on the backend entrypoint is "moved" to the frontend client. UIX supports multiple methods for backend rendering.

3. Backend and frontend entrypoints (route merging)

When entrypoint exports for both the frontend and the backend are available, they are automatically merged. This configuration normally only makes senses in combination with Entrypoint Routes.

The following diagram visualizes the concept of route merging in UIX: d

Backend routes are always prioritized over frontend routes.

In this example, the route /support/technical follows the frontend entrypoint route and resolves to Tech Support. The route /home/about is resolved on the backend to About us.

Entrypoint values

HTML elements

HTML Elements are directly appended to the document body. They can be created with normal DOM APIs (document.createElement()) or with JSX syntax:

import { Entrypoint } from "uix/html/entrypoints.ts";
export default <div>Content</div> satisfies Entrypoint;

Like other entrypoint values, HTML Elements are DATEX compatible and their content can be synchronized. Keep in mind that the content is not updated when it is provided with renderStatic.

const counter = $$(0);

export default <div>Count: {counter}</div> satisfies Entrypoint


Strings are displayed as text appended to the document body (color and background color depends on the current App theme).


export default "Hi World" satisfies Entrypoint
const content = $$("content");
export default content satisfies Entrypoint;
content.val = "new content"

(If you only want to display plain text without a parent HTML document and CSS styles, you can use provideContent("text content"))

Route maps

Route maps are simple JavaScript objects with route patterns as keys and entrypoint values as values.

When a URL is requested from the backend or loaded on the frontend, the most specific (longest) matching route entry is resolved to an entrypoint value.

A simple Route Map could look like this:

export default {
    '/home': <HomePage/>,
    '/about': <div>About us...</div>
} satisfies Entrypoint

Since Route Maps are valid Entrypoint values, multiple Route Maps can be nested. Because a route part must exactly match the route pattern key, the parent route key must end with * for the route to be followed.

export default {
    '/articles/*': {
        '/first': 'First Article...',
        '/second': 'Second Article...'
} satisfies Entrypoint

Besides the * syntax, many more patterns, like Regular Expressions, are supported in the Route Map keys. Internally, Route Maps use the URLPattern API. Matches can be accessed via the second argument in the callback function. The raw URLPatternResult can be acessed via ctx.urlPattern.

export default {
    // Match user route with name
    '/user/:name/': (_, {name}) => `Hello ${name}!`
    // Match page route using a Regular Expression
    '/page/(1|2|3)/': (ctx) => `This is page ${ctx.urlPattern.pathname.groups[0]}` 
    // Fallback if nothing else matches
    '*': 'Not found' 
} satisfies Entrypoint

Route map filters

Route Maps also accept special symbols, called filters as keys. They can be used to follow a specific route only if a certain condition is met.

One important use cases for filters are the RequestMethod filters that can be used to route depending on the HTTP request method:

import { RequestMethod } from "uix/routing/request-methods.ts"

export default {
    '/login': {
        // Provide login page
        [RequestMethod.GET]: provideFile("./common/index.html"),
        // Handle POST method triggered from login page    
        [RequestMethod.POST]: (ctx) => handleLogin(ctx)
} satisfies Entrypoint

Custom route filters can be created with the createFilter() method from "uix/routing/route-filter.ts":

const isAdmin = createFilter((ctx: Context) => ctx.privateData.isAdmin)
const isPayingCustomer = createFilter((ctx: Context) => ctx.privateData.isPayingCustomer)

export default {
    '/api/*': {
        [isAdmin]:          ctx => handleAPICall(ctx, {rateLimit: Infinity}).
        [isPayingCustomer]: ctx => handleAPICall(ctx, {rateLimit: 1000}),
        '*' :               ctx => handleAPICall(ctx, {rateLimit: 10}),
} satisfies Entrypoint

In this example, API calls are triggered with different rate limits depending on the type of the requesting client. The wildcard ('*') selector can be used like with normal routes to provide a fallback behaviour if none of the other cases match.


Blobs are directly displayed as files in the browser (Creating a file response with the correct mime type).


export default datex.get('./image.png') satisfies Entrypoint

Filesystem files

In a deno environment, Deno.FSFile values can be returned as entrypoint values. They create a file response with the correct mime type.

The provideFile() function can also be used to return files from the local file system.

import { provideFile } from "uix/html/entrypoint-providers.tsx";

export default provideFile('./image.png') satisfies Entrypoint


URL objects result in a redirect response (HTTP Status Code 304) to the given URL. This can also be achieved with provideRedirect():

import { provideRedirect } from "uix/html/entrypoint-providers.tsx";

export default provideRedirect('https://example.unyt.app') satisfies Entrypoint

Virtual redirects

Virtual redirects are similar to normal redirects, but they directly return a response with the content of the redirect URL, not a redirect response (HTTP Status 304).

import { provideVirtualRedirect } from "uix/html/entrypoint-providers.tsx";

export default provideVirtualRedirect('/example/home') satisfies Entrypoint

Entrypoint functions

In the example above, an Entrypoint Function is used to return custom content based on the context of a route. Entrypoint Functions take a single argument, a Context object and return a Entrypoint or Promise<Entrypoint>


export default (ctx: Context) => {
    return `You visited this page from ${ctx.request.address} and your language is ${ctx.language}`
} satisfies Entrypoint

When an entrypoint function throws an error, the error value is returned like a normal return value, but with an HTTP Status Code 500.

UIX components

UIX components implement the Route Manager interface and can handle routes internally. When a component is encountered in the route chain, the onRoute method is called on the component.

class Component {
    // return the child element to which the route is resolved
    // if the route contains more sections, onRoute is called on this child element with the next route
    // section as the identifier
    onRoute(identifier:string, is_initial_route:boolean):Component|boolean|void
    // return internal state of last resolved route
    getInternalRoute(): Path.route_representation|Promise<Path.route_representation> 


Component routing can be used to display or focus on different child components depending on the route.

class Parent extends Component {
    #activeChild?: HTMLElement

    override onRoute(identifier:string) {
        // find the child that has the same id as the identifier
        this.#activeChild = this.shadowRoot.querySelector(`#${identifier}`);
        return this.#activeChild;

    override getInternalRoute() {
        return [this.#activeChild.id]

export default {
    // content for /about
    '/about': 'About us', 
    // content for /version
    '/version': 1,  

    // content for all other routes
    // e.g. /a -> div#a is focused
    '*': <Parent>
            <div id="a">A</div>
            <div id="b">B</div>
            <div id="c">C</div>

Error handling

Throwing values

Values that are thrown with throw from an entrypoint function are treated similarly to returned values - the value is still rendered in the browser. There is only one difference: The response has an error status code instead of the default status code 200.

export default {
    '/:id': (_, { id }) => {
         if (id !== "4269420")
             throw "Invalid login"; // displays "Invalid login" with status code 500
         return "The secret is 42!"; // displays "The secret is 42!" with status code 200
} satisfies Entrypoint;

Throwing errors

Instances of Error that are thrown or returned from an entrypoint function are rendered in the browser as an error info box (including a stack trace when running in dev stage).

export default {
    '/:id': (_, { id }) => {
         if (id !== "4269420")
             throw new Error("Invalid login"); // displays an error info box (with stack trace)
         return "The secret is 42!";
} satisfies Entrypoint;


HTTPStatus values can be returned or thrown to create a response with a specific status code. Additionally, custom content can be returned using the with method:

import { HTTPStatus } from "uix/html/http-status.ts";
export default {
    '/:id': (_, { id }) => {
         if (id !== "4269420")
             throw HTTPStatus.BAD_REQUEST.with("MyCustomMessage"); // displays "MyCustomMessage" with status code 400 (Bad Request)
         return "The secret is 42!";
} satisfies Entrypoint;

UIX providers

UIX provider utility functions allow backend entrypoint to directly return HTTP Responses from an entrypoint.

List of UIX providers:

  • function provideValue(value:unknown, options?:{type?:Datex.DATEX_FILE_TYPE, formatted?:boolean})
    This function returns a HTTP Response with the mime type application/json, application/datex or text/datex, containing the serialized value. When the options.type is Datex.DATEX_FILE_TYPE.JSON, the value must be serializable with JSON.stringify. The default value for options.type is Datex.FILE_TYPE.DATEX_SCRIPT. In this configuration, any DATEX-compatible value can be provided.
  • function provideJSON(value:unknown, options?:{formatted?:boolean})
    This function returns a HTTP Response with the mime type application/json, containing the serialized value. The value must be JSON-compatible.
  • function provideContent(content:string|ArrayBuffer, type:mime_type = "text/plain;charset=utf-8", status?:number)
    Returns a HTTP Response with custom content and a custom mime type and status code.

Route handlers

Route handlers are similar to Dynamic Entrypoint Functions, but they are represented with an interface. In contrast to a Dynamic Entrypoint Function, which only take a UIX Context as a parameter, the getRoute method of a Route Handlers additionally takes the remaining route as an argument.

export interface RouteHandler {
    // return entrypoint for a route
    getRoute(route:Path.Route, context:Context): Entrypoint|Promise<Entrypoint> 

Route managers

The RouteManager interface represents an entity with an internal route state. In contrast to other entrypoints, it can modify the request route.

When a Route Manager is encountered while resolving a route, the resolveRoute method is called with the remaining part of the current route. The Route Manager decides how to update its internal state and returns the part of the route that it could resolve. The actual route on the client is updated to only contain this part. The getInternalRoute should always return the route represented by the current state, and should match the route part returned by resolveRoute.

The RouteManager interface is implemented by UIX Components.

interface RouteManager {
    // return part of route that could be resolved
    resolveRoute(route: Path.Route, context: Context): Path.route_representation | Promise<Path.route_representation> 
    // return internal state of last resolved route
    getInternalRoute(): Path.route_representation | Promise<Path.route_representation> 

Entrypoint proxies

An Entrypoint Proxy can be wrapped around any Entrypoint value to intercept routing and add custom functionality. The abstract EntrypointProxy class has two methods that can be implemented:

abstract class EntrypointProxy implements RouteHandler {
     * This method is called before a route is resolved by the entrypoint
     * It can be used to implement a custom routing behaviour
     * for some or all routes, overriding the entrypoint routing
     * The returned value replaces the entrypoint, if not null
     * @param route requested route
     * @param context UIX context
     * @returns entrypoint override or null
    abstract intercept?(route: Path.Route, context: Context): void|Entrypoint|Promise<void|Entrypoint>

     * This method is called after a route was resolved by the entrypoint
     * It can be used to override the content provided for a route by returning 
     * a different entrypoint value. 
     * When null is returned, the route content is not changed
     * @param content content as resolved by entrypoint
     * @param render_method render method as resolved by entrypoint
     * @param route the requested route
     * @param context UIX context
     * @returns entrypoint override or null
    abstract transform?(content: Entrypoint, render_method: RenderMethod, route: Path.Route, context: Context): void | Entrypoint | Promise<void | Entrypoint>


A UIX Context is created for each entrypoint request (when requesting a URL from a backend entrypoint or when redirecting to a URL on the frontend) and can be accessed in Dynamic Entrypoint Functions, Route Managers and Route Handlers. It contains information about the client, about the route, and about the HTTP request (only on backend entrypoints).

interface Context {
    request?: Request
    requestData = {
        address: string | null

    path: string
    params: Record<string,string>;
    urlPattern?: URLPatternResult
    searchParams: URLSearchParams

    language: string
    endpoint: Datex.Endpoint

    getSharedData(): Promise<Record<string, unknown>>
    getPrivateData(): Promise<Record<string, unknown>>

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