ui5-typescript-conversion

name	ui5-typescript-conversion
description	A skill for converting UI5 (SAPUI5/OpenUI5) projects to TypeScript.

UI5 TypeScript Conversion Guidelines

This document outlines how a UI5 (SAPUI5/OpenUI5) project can be converted to TypeScript. It consists of the following parts:

1. Important general rules
2. How the setup of the project needs to be changed
3. Converting the code itself
4. Converting tests (reference to separate file)

General Conversion Rules

Preserve ALL comments

You MUST preserve existing JSDoc, documentation and comments - never remove JSDoc or comments during the conversion.

Example input:

/**
 * My cool controller, it does things.
 */
return Controller.extend("com.myorg.myapp.controller.BaseController", {
    /**
     * Convenience method for accessing the component of the controller's view.
     * @returns {sap.ui.core.Component} The component of the controller's view
     */
    getOwnerComponent: function () {
        // comment
        return Controller.prototype.getOwnerComponent.call(this);
    },
    ...
});

Wrong output:

export default class BaseController extends Controller {
    public getOwnerComponent(): UIComponent {
        return super.getOwnerComponent() as UIComponent;
    }
}

Correct output:

/**
 * My cool controller, it does things.
 * @namespace com.myorg.myapp.controller
 */
export default class BaseController extends Controller {
    /**
     * Convenience method for accessing the component of the controller's view.
     * @returns {sap.ui.core.Component} The component of the controller's view
     */
    public getOwnerComponent(): UIComponent {
        // comment
        return super.getOwnerComponent() as UIComponent;
    }
}

Be diligent

Carefully respect all guidelines in this document (and adapt appropriately where required). Before each conversion step, consider all relevant details from this document.

Go step-by-step

You should convert the project step by step, starting with the TypeScript project setup and then the most central files on which other files depend, so those other files can use the typed version of those central files once they are converted as well. "allowJs": true in the tsconfig.json's compilerOptions may be useful to run semi-converted projects if needed.

Avoid any type

Do not take shortcuts, but try to find the proper type or create an interface instead of any.

BAD:

(this.getOwnerComponent() as any).getContentDensityClass();

GOOD:

(this.getOwnerComponent() as AppComponent).getContentDensityClass()

Avoid unknown casts

Import and use actual UI5 control types instead (either the base class sap/ui/core/Control or more specific classes if needed to access the respective property). Inspect the XMLView to find out which control type you actually get when calling this.byId(...) in a controller! Don't forget using the specific event types like e.g. Route$PatternMatchedEvent for routing events.

Casting Example

BAD:

(this.byId("form") as unknown as {setVisible: (v: boolean) => void}).setVisible(false);

GOOD:

import SimpleForm from "sap/ui/layout/form/SimpleForm";
(this.byId("form") as SimpleForm).setVisible(false);

Create shared type definitions

Many type definitions you create are useful in different files. Create those in a central location like a file in src/types/.

Project Setup Conversion

1. package.json

You must add the following dev dependencies in the package.json file (very important) if they are not already present:

{{dependencies}}

However, if a dependency is already present in package.json, do not increase the major version number of it. Do not remove existing dependencies, you must only add new configuration. Install the dependencies early to verify the types are found.

IMPORTANT: In addition, you MUST also add the @sapui5/types (or @openui5/types) package in a version matching the UI5 project as dev dependency. Framework type and version can be found in ui5.yaml or using the get_project_info MCP tool.

In addition, if (and ONLY if) dependencies or their versions changed, ensure (or tell the user) to execute npm install / yarn install (whatever is used in the project) to get the changed dependencies in the project.

The typescript-eslint dependency is only relevant when the project already has an eslint setup (details are below).

Also add the "ts-typecheck": "tsc --noEmit" script to package.json, so you and the developer can easily check for TypeScript errors.

2. tsconfig.json

Add a tsconfig.json file. Use the following sample as reference, but adapt to the needs of the current project, e.g. adapt the paths map:

{
	"compilerOptions": {
		"target": "es2023",
		"module": "es2022",
		"moduleResolution": "node",
		"skipLibCheck": true,
		"allowJs": true,
		"strict": true,
		"strictNullChecks": false,
		"strictPropertyInitialization": false,
		"outDir": "./dist",
		"rootDir": "./webapp",
		"types": ["@sapui5/types", "@types/jquery", "@types/qunit"],
		 
			 
			 
			 
		
	
	 
	 

3. ui5.yaml

Update the ui5.yaml file to use the ui5-tooling-transpile-task and ui5-tooling-transpile-middleware and ensure that at least the following config is present:

builder:
  customTasks:
    - name: ui5-tooling-transpile-task
      afterTask: replaceVersion
server:
  customMiddleware:
    - name: ui5-tooling-transpile-middleware
      afterMiddleware: compression
    - name: ui5-middleware-livereload
      afterMiddleware: compression

Ensure that the generated ui5.yaml file is valid - avoid duplicate entries, each root configuration must only exist once. If a configuration like server already exists, you must add to it instead of adding a second entry.

4. Eslint configuration

Only when the project has eslint set up, enhance the eslint configuration with TypeScript-specific parts. If eslint is not set up with dependency in package.json and an eslint config, then do nothing. A complete eslint v9 compatible eslint.config.mjs file could e.g. look like this, but the actual content depends on the specific project, so you MUST adapt it!

import eslint from "@eslint/js";
import globals from "globals";
import tseslint from "typescript-eslint";

export default tseslint.config(
	eslint.configs.recommended,
	...tseslint.configs.recommended,
	...tseslint.configs.recommendedTypeChecked,
	{
		languageOptions: {
			globals: {
				...globals.browser,
				sap: "readonly"
			},
			ecmaVersion: 2023,
			parserOptions: {
				project: true,
				tsconfigRootDir: import.meta.dirname
			}
		}
	},
	{
		ignores: ["eslint.config.mjs"]
	}
);

Application Code Conversion

Step 1: Change proprietary UI5 class syntax to standard ES class syntax

Every UI5 class definitions (SuperClass.extend(...)) must be converted to a standard JavaScript class. The properties in the UI5 class configuration object (second parameter of extend) become members of the standard JavaScript class. It is important to annotate the class with the namespace in a JSDoc comment, so the back transformation can re-add it. This @namespace comment MUST immediately precede the class declaration. The namespace is the part of the full package+class name (first parameter of extend) that precedes the class name.

Before (example):

[... other code, e.g. loading the dependencies "App", "Controller" etc. ...]
 
var App = Controller.extend("ui5tssampleapp.controller.App", {
    onInit: function _onInit() {
        // apply content density mode to root view
        this.getView().addStyleClass(this.getOwnerComponent().getContentDensityClass());
    }
});

After (example, do not use this code verbatim):

[... other code, e.g. loading the dependencies "App", "Controller" etc. ...]
 
/**
* @namespace ui5tssampleapp.controller
*/
class App extends Controller {
    public onInit() {
        // apply content density mode to root view
        this.getView().addStyleClass((this.getOwnerComponent()).getContentDensityClass());
    };
};

Step 2: Change to ECMAScript modules and imports

TypeScript UI5 apps must use modern ES modules and imports. Hence, convert all UI5 module definition and dependency loading calls (sap.ui.require(...), sap.ui.define(...)) to ES modules with imports (and in case of sap.ui.define a module export).

In the above example, this looks as follows.

Before:

sap.ui.define(["sap/ui/core/mvc/Controller"], function (Controller) {
    /**
     * @namespace ui5tssampleapp.controller
     */
    class App extends Controller {
        ... // as above
    };
 
  return App;
});

After:

import Controller from "sap/ui/core/mvc/Controller";
 
/**
* @namespace ui5tssampleapp.controller
*/
export default class App extends Controller {
    ... // as above
};

sap.ui.require shall be converted to just the imports and no export. Avoid name clashes for the imported modules.

Hint: importing sap/ui/core/Core does not provide the class (like for most other UI5 modules), but the singleton instance of the UI5 Core. So the imported module can be used directly for methods like byId(...) instead of calls to sap.ui.getCore() which return the singleton in JavaScript.

When sap.ui.require is used dynamically, e.g. sap.ui.require(["sap/m/MessageBox"], function(MessageBox) { ... }) inside a method body, then convert this to a dynamic import like import("sap/m/MessageBox").then((MessageBox) => { ... }).

Step 3: Standard TypeScript Code Adaptations

Apply your general knowledge about converting JavaScript code to TypeScript. In particular:

• Add type information to method parameters and variables where needed.
• Add missing private member class variables (with type information) to the beginning of the class definition. (In JavaScript they are often created later on-the-fly during the lifetime of a class instance.)
• Convert conventional functions to arrow functions when someFunction.bind(...) is used because TypeScript does not seem to propagate the type of the bound "this" context into the function body.
• Define further types and structures needed within the code, if applicable.

IMPORTANT: whenever you use a UI5 type, e.g. for annotating a variable or method parameter/returntype, do NOT use the UI5 type with its global namespace (like sap.m.Button or sap.ui.core.Popup)! Instead, import this UI5 type from the respective module (like sap/m/Button or sap/ui/core/Popup - add an import if needed) and use the imported module.

Example:

Wrong:

const b: sap.m.Button;
function getPopup(): sap.ui.core.Popup  { ... }

Correct:

import Button from "sap/m/Button";
import Popup from "sap/ui/core/Popup";
 
const b: Button;
function getPopup(): Popup  { ... }

Hint: use the actual UI5 control events, not browser events like Event or MouseEvent, in event handlers of UI5 controls. UI5 events are different. E.g. use the Button$PressEvent and Button$PressEventParameters from the sap/m/Button module when the press event of the sap/m/Button is handled.

Note: for any event XYZ of a UI5 control ABC, types like ABC$XYZEvent and ABC$XYZEventParameters are available!

Example:

Before:

sap.ui.define(["./BaseController"], function (BaseController) {
    return BaseController.extend("my.app.controller.Main", {
        onPress: function(oEvent) {
            const button = oEvent.getSource();
        },
        
        onSelectionChange: function(oEvent) {
            const items = oEvent.getParameter("selectedItems");
        }
    });
});

After:

import BaseController from "./BaseController";
import Button from "sap/m/Button";
import {Button$PressEvent} from "sap/m/Button";
import {Table$RowSelectionChangeEvent} from "sap/ui/table/Table";

export default class Main extends BaseController {
    onPress(oEvent: Button$PressEvent): void {
        const button = oEvent.getSource() as Button;
    }
    
    onRowSelectionChange(oEvent: Table$RowSelectionChangeEvent): void {
        const selectedContext = oEvent.getParameter("rowContext");
    }
}

Hint: use the most specific type which does provide all needed properties. Examples:

• Use specific types like KeyboardEvent or MouseEvent, not just Event for browser events.
• Use the Button$PressEvent from the sap/m/Button module, not the sap/ui/base/Event.
• The same is valid for all types, not only events.

Step 4: Casts for Return Values of Generic Methods

Generic getter methods like document.getElementById(...) or someUI5Control.getModel() or inside a controller this.byId() return the super-type of all possible types (in the examples HTMLElement and sap.ui.model.Model and sap.ui.core.Element) although in practice it will usually be a specific sub-type (e.g. an HTMLAnchorElement or a sap.ui.model.odata.v4.ODataModel or a sap.m.Input).

In many cases you will have to cast the return value to the specific type to use it. The actual type can usually be derived from the context. If not, rather avoid the cast than guessing a wrong one. Also, do not cast to a superclass like sap.ui.model.Model when this is anyway the returned type.

The same is valid for several UI5 methods, most prominently the following:

• core.byId() / view.byId()
• control.getBinding()
• ownerComponent.getModel()
• event.getSource()
• component.getRootControl()
• this.getOwnerComponent()

This cast will sometimes also require an additional module import to make the type (like ODataModel above) known.

In the app controller example above, this step would add an additional import of the app's component (called AppComponent), so within the onInit implementation the required typecast can be done. Without this typecast, the return type of getOwnerComponent would be a sap.ui.core.Component, which does not have the getContentDensityClass method defined in the app component.

Before:

import Controller from "sap/ui/core/mvc/Controller";
 
/**
* @namespace ui5tssampleapp.controller
*/
export default class App extends Controller {
 
    public onInit() {
        // apply content density mode to root view
        this.getView().addStyleClass(this.getOwnerComponent().getContentDensityClass());
    };
 
};

After:

import Controller from "sap/ui/core/mvc/Controller";
import AppComponent from "../Component";
 
/**
* @namespace ui5tssampleapp.controller
*/
export default class App extends Controller {
 
    public onInit() : void {
        // apply content density mode to root view
        this.getView().addStyleClass((this.getOwnerComponent() as AppComponent).getContentDensityClass());
    };
 
};

(Note: the "void" definition of the method return type is not strictly demanded by TypeScript, but is beneficial e.g. depending on the linting settings.)

Step 5: Solving any Remaining Issues

At this point, the number of remaining TypeScript errors should be vastly reduced. If you clearly recognize some, fix them, but in case of doubt mention the last remaining issues to the developer.

UI5 Control TypeScript Conversion Guidelines

This section covers the conversion of UI5 custom controls from JavaScript to TypeScript. This applies both to single custom controls within applications and to control libraries.

Converting custom UI5 controls to TypeScript requires specific patterns in addition to the general TypeScript conversion (converting the proprietary UI5 class and syntax).

The Runtime-Generated Methods Problem (CRITICAL)

This is the most important aspect to understand.

UI5 generates getter/setter (and more) methods for all properties, aggregations, associations, and events at runtime. This means TypeScript cannot see these methods at development time, causing type errors.

The Problem

In a control with a text property defined in metadata:

static readonly metadata: MetadataOptions = {
    properties: {
        "text": "string"
    }
};

TypeScript will show errors when trying to use the generated methods:

rm.text(control.getText());  // ERROR: Property 'getText' does not exist on type 'MyControl'

Additionally, TypeScript doesn't know the constructor signature structure for initializing controls:

new MyControl("myId", {text: "Hello"}); // TypeScript doesn't know about the settings object structure

This affects:

• Property getters/setters: getText(), setText(), bindText()
• Aggregation methods: addItem(), removeItem(), getItems(), ...
• Association methods: getLabel(), setLabel()
• Event methods: attachPress(), detachPress(), firePress()
• Constructor settings object structure

The Solution: @ui5/ts-interface-generator

Install the interface generator tool as a dev dependency:

npm install --save-dev @ui5/ts-interface-generator@{{ts-interface-generator-version}}

To make subsequent development easier, add a script like this to package.json:

{
    "scripts": {
        "watch:controls": "npx @ui5/ts-interface-generator --watch"
    }
}

NOTE: the tsconfig file related to the controls must be in the same directory in which the interface generator is launched. If you launch it in the root of your project and the tsconfig covering the TypeScript controls is in a subdirectory or has a different name than tsconfig.json, then call it like npx @ui5/ts-interface-generator --watch --config path/to/tsconfig.json.

After TypeScript conversion of all controls, run the generator once to generate the needed control interfaces:

npm run watch:controls

This generates a *.gen.d.ts file (e.g., MyControl.gen.d.ts) containing TypeScript interfaces with all the runtime-generated methods. TypeScript merges these interfaces with the control class.

These generated files should be committed to version control and never edited manually.

Required Constructor Signatures (CRITICAL MANUAL STEP)

After running the interface generator, you must manually copy the constructor signatures from the terminal output into the respective control class.

The generator outputs something like:

===== BEGIN =====
// The following three lines were generated and should remain as-is to make TypeScript aware of the constructor signatures 
constructor(id?: string | $MyControlSettings);
constructor(id?: string, settings?: $MyControlSettings);
constructor(id?: string, settings?: $MyControlSettings) { super(id, settings); }
===== END =====

Copy these lines into the beginning of the class body, before the metadata definition:

export default class MyControl extends Control {
    // The following three lines were generated and should remain as-is to make TypeScript aware of the constructor signatures 
    constructor(id?: string | $MyControlSettings);
    constructor(id?: string, settings?: $MyControlSettings);
    constructor(id?: string, settings?: $MyControlSettings) { super(id, settings); }

    static readonly metadata: MetadataOptions = {
        // ...
    };
}

Control Metadata Typing

The control metadata must be typed as MetadataOptions:

import type { MetadataOptions } from "sap/ui/core/Element";

export default class MyControl extends Control {
    static readonly metadata: MetadataOptions = {
        properties: {
            "text": "string"
        }
    };
}

Important points:

• Import MetadataOptions from sap/ui/core/Element for controls (or closest base class - also available for sap/ui/core/Object, sap/ui/core/ManagedObject, and sap/ui/core/Component)
• Use import type instead of import (design-time only, no runtime impact)
• MetadataOptions available since UI5 1.110; use object for earlier versions
• Typing prevents issues when inheriting from the control (inherited properties should not be repeated)

Namespace Annotation Required

The @namespace JSDoc annotation is required for the transformer to generate correct UI5 class names:

/**
 * @namespace ui5.typescript.helloworld.control
 */
export default class MyControl extends Control {
    // ...
}

Export Pattern

Must use export default immediately when defining the class, otherwise ts-interface-generator will fail:

// CORRECT:
export default class MyControl extends Control {
    // ...
}

// WRONG - separate export:
class MyControl extends Control {
    // ...
}
export default MyControl;

Static Members for Metadata and Renderer

Both metadata and renderer are defined as static class members:

import RenderManager from "sap/ui/core/RenderManager";

export default class MyControl extends Control {
    static readonly metadata: MetadataOptions = {
        properties: {
            "text": "string"
        }
    };

    static renderer = {
        apiVersion: 2,
        render: function (rm: RenderManager, control: MyControl): void {
            rm.openStart("div", control);
            rm.openEnd();
            rm.text(control.getText());
            rm.close("div");
        }
    };
}

The renderer can also be in a separate file (common in libraries) and should in this case stay separate when converting to TypeScript.

The following JavaScript code:

sap.ui.define([
    "sap/ui/core/Control",
    "./MyControlRenderer"
], function (Control, MyControlRenderer) {
    "use strict";

    return Control.extend("com.myorg.myapp.control.MyControl", {
        ...
        renderer: MyControlRenderer,
        ...

is then converted to this TypeScript code:

import Control from "sap/ui/core/Control";
import type { MetadataOptions } from "sap/ui/core/Element";
import MyControlRenderer from "./MyControlRenderer";

/**
 * @namespace com.myorg.myapp.control
 */
export default class MyControl extends Control {
    ...
    static renderer = MyControlRenderer;
    ...

Complete Control Example

JavaScript (Before):

sap.ui.define([
    "sap/ui/core/Control",
    "sap/ui/core/RenderManager"
], function (Control, RenderManager) {
    "use strict";
    
    var MyControl = Control.extend("ui5.typescript.helloworld.control.MyControl", {
        metadata: {
            properties: {
                "text": "string"
            },
            events: {
                "press": {}
            }
        },
        
        renderer: function (rm, control) {
            rm.openStart("div", control);
            rm.openEnd();
            rm.text(control.getText());
            rm.close("div");
        },
        
        onclick: function() {
            this.firePress();
        }
    });

    return MyControl;
});

TypeScript (After):

import Control from "sap/ui/core/Control";
import type { MetadataOptions } from "sap/ui/core/Element";
import RenderManager from "sap/ui/core/RenderManager";

/**
 * @namespace ui5.typescript.helloworld.control
 */
export default class MyControl extends Control {
    // The following three lines were generated and should remain as-is to make TypeScript aware of the constructor signatures 
    constructor(id?: string | $MyControlSettings);
    constructor(id?: string, settings?: $MyControlSettings);
    constructor(id?: string, settings?: $MyControlSettings) { super(id, settings); }

    static readonly metadata: MetadataOptions = {
        properties: {
            "text": "string"
        },
        events: {
            "press": {}
        }
    };

    static renderer = {
        : ,
        :  ():  {
            rm.(, control);
            rm.();
            rm.(control.());
            rm.();
        }
    };

    ():  {
        .();
    }
}

Library-Specific Guidelines

When converting entire control libraries (not just single controls in apps), additional steps are required:

Library Module with Enums (CRITICAL to avoid XSS issues!)

In library.ts, enums must be attached to the global library object for UI5 runtime compatibility:

import ObjectPath from "sap/base/util/ObjectPath";

// Define enum as TypeScript enum
export enum ExampleColor {
    Red = "Red",
    Green = "Green",
    Blue = "Blue"
}

// CRITICAL: Attach to global library object
const thisLib = ObjectPath.get("com.myorg.myui5lib") as {[key: string]: unknown};
thisLib.ExampleColor = ExampleColor;

Why this is critical for every enum in the library:

• Control properties reference types as global names: type: "com.myorg.myui5lib.ExampleColor"
• UI5 runtime needs to find the enum via this global path
• Without this, UI5 cannot validate the property type
• This breaks type checking and can create XSS vulnerabilities as unchecked content can be written to HTML unexpectedly

Path Mapping in tsconfig.json

For libraries, add path mappings for the library namespace:

{
    "compilerOptions": {
        "paths": {
            "com/myorg/mylib/*": ["./src/*"]
        }
    }
}

Control Conversion Checklist

When converting a control from JavaScript to TypeScript:

1. Convert to ES6 class/module like regular UI5 modules
2. Add @namespace JSDoc annotation
3. Use export default immediately with class definition
4. Type metadata as MetadataOptions (import from appropriate base class)
5. Define metadata and renderer as static members
6. Install and run @ui5/ts-interface-generator
7. Copy constructor signatures from generator output into class
8. If in a library: manually attach enums to global library object
9. Preserve all JSDoc comments and documentation

Test Conversion

There are critical, non-obvious patterns for converting UI5 test code from JavaScript to TypeScript. See the test conversion document for details when tests need to be converted..