ArkTS syntax, migration, and optimization guide for HarmonyOS/OpenHarmony development. Triggers on: .ets files, ArkTS keywords, HarmonyOS/OpenHarmony context, @ohos packages. Help with syntax reference, TypeScript migration, performance optimization, compile errors, state management, component devel

ArkTS Syntax Assistant [中文文档](SKILL.zh.md) Overview ArkTS is the default development language for OpenHarmony applications. It builds upon TypeScript with enhanced static typing to improve program stability and performance. Core Features Static Typing : All types determined at compile time, reducing runtime checks No Dynamic Object Layout : Object structure fixed at compile time, cannot be modified at runtime Restricted Operators : Some operator behaviors are restricted to encourage clearer code semantics No Structural Typing : Structural typing is currently not supported Reference Documentation Scenario Document Syntax Learning [references/en/introduction to arkts.md](references/en/introduction to arkts.md) Quick Overview [references/en/arkts get started.md](references/en/arkts get started.md) TS Migration [references/en/typescript to arkts migration guide.md](references/en/typescript to arkts migration guide.md) Migration Background [references/en/arkts migration background.md](references/en/arkts migration background.md) Performance [references/en/arkts high performance programming.md](references/en/arkts high performance programming.md) More Cases [references/en/arkts more cases.md](references/en/arkts more cases.md) Workflows 1. Syntax Questions Common Syntax Questions : Variable declaration Use let / const with explicit type or inference Function definition Supports optional parameters, defaults, rest parameters, arrow functions Classes and interfaces Must initialize fields, supports inheritance and implementation Generics Supports constraints and default values Null safety Nullable types ((T null)), non null assertion ((!)), optional chaining ((?.)) 2. TypeScript Migration Key Migration Rules Quick Reference : TypeScript ArkTS Alternative var x let x any / unknown Specific types {n: 42} object literal Define class/interface first [index: T]: U index signature Record<T, U A & B intersection type interface C extends A, B function(){} function expression () = {} arrow function <Type value type assertion value as Type Destructuring [a, b] = arr Individual access arr[0] , arr[1] for..in for loop or for..of Constructor parameter properties Explicit field declaration 3. Performance Optimization High Performance Programming Key Points : Declarations : Use const for invariants; avoid mixing integer and float Loops : Extract loop invariants; avoid numeric overflow Functions : Parameter passing preferred over closures; avoid optional parameters Arrays : Use TypedArray for numeric values; avoid sparse arrays and union type arrays Exceptions : Avoid throwing in loops; use return values instead 4. Compile Error Resolution Common Questions Q: How to handle JSON.parse return value? Q: How to define object types? Q: How to replace globalThis? Q: How to handle error types in catch? Q: How to use Record type? Q: How to replace constructor signatures with factory functions? Prohibited Standard Library APIs The following are prohibited in ArkTS: Global : eval Object : proto , defineProperty , freeze , getPrototypeOf , etc. Reflect : apply , construct , defineProperty , etc. Proxy : All handler methods Build Scripts The scripts directory provides quick compilation scripts for ArkTS projects (including dependency installation): Platform Script Purpose macOS/Linux scripts/run.sh Execute ohpm install + hvigorw assembleApp Windows scripts/run.ps1 Execute ohpm install + hvigorw assembleApp Usage: Script execution steps: 1. Install dependencies ( ohpm install all ) 2. Build project ( hvigorw assembleApp ) Mandatory Requirements CRITICAL : When this skill generates ArkTS code, the following workflow MUST be followed: 1. Compilation Verification : After generating code, you MUST compile the project using the build scripts: macOS/Linux: bash scripts/run.sh Windows: .\scripts\run.ps1 2. Retry Strategy : If compilation fails: Analyze the error output Fix the issue and retry compilation Maximum of 3 compilation attempts 3. User Intervention : After 3 failed compilation attempts, use AskUserQuestion : 4. Error Reporting : Always show the full compilation error output when failures occur. Answer Guidelines 1. Prioritize code examples : Show correct vs incorrect syntax comparison 2. Reference official documentation : For detailed explanations, guide users to consult corresponding documents in references/ 3. Explain reasons : Explain why ArkTS has this restriction (performance, stability) 4. Provide alternatives : For unsupported features, provide feasible alternatives License MIT License see [LICENSE.txt](LICENSE.txt)

arkts-syntax-assistant