Typescript Standards · TS

• TypeScript Class Design Standards | TS-01

  • Types
    • Use type annotations for function parameters and return types | TS-01.1 |
    • Use type annotations variables of complex objects | TS-01.2 |
    • Use const over let for variables that do not change | TS-01.3 |
    • Use unknown over any | TS-01.4 |
    • Use readonly for properties that won’t change after initialisation | TS-01.5 |
      • readonly example (✅)
    • Use undefined over null | TS-01.6 |
    • Use optional parameters | TS-01.7 |
    • Avoid redundant type annotations when TypeScript can infer types | TS-01.8 |
  • Object-Oriented Programming
    • Use interfaces to define object structures | TS-01.9 |
    • Use classes to define objects | TS-01.10 |

• TypeScript Maintainability Standards | TS-02

  • Methods do not exceed 10 statements | TS-02.1 |
  • Do not duplicate code | TS-02.2 |
  • Nested control statements do not exceed a depth of 2 | TS-02.3 |
  • Do not allow methods with more than 4 parameters | TS-02.4 |
  • Do not use magic numbers or strings | TS-02.5 |
  • Use Enums over fixed sets of constants | TS-02.6 |
  • Allow gaps between numeric values for enums | TS-02.7 |
  • Don’t comment out code | TS-02.8 |
  • Target specific versions or version ranges in package.json | TS-02.9 |
  • Implement error logging for observability of problems | TS-02.10 |
  • Limit the contents of a source code file to one type | TS-02.11 |
  • Enable strictNullChecks for Type safety | TS-02.12 |
  • Optimise imports | TS-02.13 |
    • Use relative imports | TS-02.14 |
    • Configure aliases for improved readability | TS-02.15 |

• TypeScript Naming Standards | TS-03

  • Files must follow the naming convention {description}.{type}.{file extension} | TS-03.1 |
  • The type within the file name should use the conventional names | TS-03.2 |
  • Symbols must use pascal case (PascalCase) | TS-03.3 |
  • Symbols must avoid private property prefix | TS-03.4 |
  • Components must use kebab case (kebab-case) | TS-03.5 |
  • The symbol must be suffixed with the word Component | TS-03.6 |
  • Component selectors should be prefixed to describe its use | TS-03.7 |
  • Directives must use camel case (camelCase) | TS-03.8 |
  • The symbol must be suffixed with the word Directive | TS-03.9 |
  • Directive selectors should be prefixed to describe its use | TS-03.10 |
  • Pipes must use camel case (camelCase) | TS-03.11 |
  • The symbol must be suffixed with the word Pipe | TS-03.12 |
  • Pipe selectors should be prefixed to describe their use | TS-03.13 |
  • The symbol must be suffixed with the word Module | TS-03.14 |
  • Modules should be named after the feature and folder that they reside in | TS-03.15 |

• TypeScript Performance and Optimisation Standards | TS-04

  • Lazy load non-critical resources | TS-04.1 |
    • Lazy loading examples

• Writing Cypress Automated Tests in TypeScript
• Writing Playwright Automated Tests in TypeScript

In general, the Airbnb standards are the basis for Typescript coding standards.

These are, where possible, enforced through the use of ESLint. The Audacia ESLint npm package contains some default ESLint configuration for JavaScript and TypeScript projects.