Google JavaScript Best Practices
Comprehensive JavaScript style and best practices guide based on Google's official JavaScript Style Guide, designed for AI agents and LLMs. Contains 47 rules across 8 categories, prioritized by impact to guide automated refactoring and code generation.
When to Apply
Reference these guidelines when:
Writing new JavaScript or ES6+ code Structuring modules and managing imports/exports Adding JSDoc type annotations and documentation Reviewing code for naming and style consistency Refactoring existing JavaScript code Rule Categories by Priority Priority Category Impact Prefix 1 Module System & Imports CRITICAL module- 2 Language Features CRITICAL lang- 3 Type Safety & JSDoc HIGH type- 4 Naming Conventions HIGH naming- 5 Control Flow & Error Handling MEDIUM-HIGH control- 6 Functions & Parameters MEDIUM func- 7 Objects & Arrays MEDIUM data- 8 Formatting & Style LOW format- Quick Reference 1. Module System & Imports (CRITICAL) module-avoid-circular-dependencies - Prevent loading failures from circular imports module-file-extension-in-imports - Include .js extension in import paths module-named-exports-over-default - Prefer named exports for consistency module-no-duplicate-imports - Import from same file only once module-no-import-aliasing - Keep original export names module-source-file-structure - Follow standard file structure order 2. Language Features (CRITICAL) lang-const-over-let-over-var - Use const by default, never var lang-es6-classes-over-prototypes - Use class syntax over prototype manipulation lang-explicit-semicolons - Always use explicit semicolons lang-no-eval - Never use eval or Function constructor lang-no-modify-builtins - Never modify built-in prototypes lang-no-non-standard-features - Use only standard ECMAScript features lang-no-primitive-wrappers - Never use primitive wrapper objects lang-no-with-statement - Never use the with statement 3. Type Safety & JSDoc (HIGH) type-cast-with-parentheses - Use parentheses for type casts type-enum-annotations - Annotate enums with static literal values type-explicit-nullability - Use explicit nullability modifiers type-jsdoc-required-for-exports - Require JSDoc for exported functions type-template-parameters - Always specify template parameters type-typedef-for-complex-types - Use typedef for complex object types 4. Naming Conventions (HIGH) naming-constant-case-for-constants - Use CONSTANT_CASE for immutable values naming-descriptive-over-brief - Prefer descriptive names over brevity naming-file-naming-conventions - Use lowercase with dashes or underscores naming-lowercamelcase-for-methods - Use lowerCamelCase for methods and variables naming-no-dollar-prefix - Avoid dollar sign prefix in identifiers naming-uppercamelcase-for-classes - Use UpperCamelCase for classes 5. Control Flow & Error Handling (MEDIUM-HIGH) control-comment-empty-catch - Document empty catch blocks control-for-of-over-for-in - Prefer for-of over for-in control-strict-equality - Use strict equality except for null checks control-switch-default-last - Always include default case in switch control-throw-error-objects - Always throw Error objects 6. Functions & Parameters (MEDIUM) func-arrow-functions-for-nested - Prefer arrow functions for nested functions func-arrow-parentheses - Always use parentheses around arrow params func-default-parameters - Use default parameters instead of conditionals func-rest-parameters-over-arguments - Use rest parameters over arguments func-spread-over-apply - Use spread operator instead of apply 7. Objects & Arrays (MEDIUM) data-array-literals-over-constructor - Use array literals over Array constructor data-destructuring-for-multiple-values - Use destructuring for multiple properties data-no-mixing-quoted-unquoted-keys - Never mix quoted and unquoted keys data-object-literals-over-constructor - Use object literals over constructor data-spread-over-concat-slice - Use spread over concat and slice data-trailing-commas - Use trailing commas in multi-line literals 8. Formatting & Style (LOW) format-braces-required - Always use braces for control structures format-column-limit - Limit lines to 80 characters format-one-statement-per-line - Place one statement per line format-single-quotes - Use single quotes for string literals format-two-space-indent - Use two-space indentation How to Use
Read individual reference files for detailed explanations and code examples:
Section definitions - Category structure and impact levels Rule template - Template for adding new rules Full Compiled Document
For a complete compiled guide with all rules, see AGENTS.md.
Reference Files File Description AGENTS.md Complete compiled guide with all rules references/_sections.md Category definitions and ordering assets/templates/_template.md Template for new rules metadata.json Version and reference information