Tagged templates process template literals with custom functions. Here's how to use them.
Basic Syntax#
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Building Custom Tags#
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HTML Escaping#
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SQL Query Builder#
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CSS-in-JS#
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Logging with Context#
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i18n Translation#
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GraphQL Queries#
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Regular Expressions#
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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.