Tagged templates process template literals with custom functions. Here's how to use them.
Basic Syntax
Building Custom Tags
HTML Escaping
SQL Query Builder
CSS-in-JS
Logging with Context
i18n Translation
GraphQL Queries
Regular Expressions
Best Practices
Design:
✓ Return useful values
✓ Handle edge cases
✓ Document expected usage
✓ Consider raw strings
Security:
✓ Escape user input
✓ Use parameterized queries
✓ Validate interpolated values
✓ Mark trusted content explicitly
Performance:
✓ Cache expensive operations
✓ Avoid unnecessary processing
✓ Consider lazy evaluation
✓ Profile complex tags
Avoid:
✗ Mutating input arrays
✗ Side effects in tags
✗ Complex nested tags
✗ Ignoring raw strings
Conclusion
Tagged template literals enable powerful custom string processing for HTML escaping, SQL queries, CSS-in-JS, translations, and domain-specific languages. The tag function receives strings and values separately, allowing safe interpolation and custom transformations.