A modern, secure, and high-performance templating engine built with ReScript and Deno. Zero TypeScript, zero Node.js.
[](https://rescript-lang.org/) [](https://deno.land/) [](https://github.com/Hyperpolymath/v3-templater/blob/main/RSR-PLATINUM.md) [](https://github.com/Hyperpolymath/v3-templater/blob/main/MAINTAINERS.md) [](https://github.com/Hyperpolymath/v3-templater/blob/main/.well-known/security.txt) [](https://github.com/Hyperpolymath/v3-templater/blob/main/.github/workflows/ci.yml)
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🚀 High Performance - Fast compilation and rendering with built-in caching
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🔒 Security First - XSS protection with automatic HTML escaping
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🦀 ReScript - Sound type system, no null errors, exhaustive pattern matching
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🦕 Deno - Modern runtime with built-in tooling, no node_modules
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🎨 Rich Syntax - Variables, conditionals, loops, filters, inheritance, and more
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🔧 Extensible - Custom filters, helpers, and plugin system
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📦 Zero Dependencies - No production dependencies (only he for HTML via CDN)
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🛠️ Built-in Tools - No jest, eslint, prettier needed - Deno includes them all
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✅ Well Tested - Comprehensive test coverage with Deno test
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🏆 RSR Compliant - PLATINUM level Rhodium Standard Repository compliance
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🌍 Community Driven - TPCF Perimeter 3 (fully open contribution)
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🤖 Multi-CI - GitHub Actions + GitLab CI pipelines
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🐳 Container Ready - Docker and docker-compose support
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📝 ADRs - Architecture Decision Records documented
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⚡ WASM Ready - Easy path to WebAssembly for performance
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[Deno](https://deno.land/) 1.38 or later
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[ReScript](https://rescript-lang.org/) 11.0 or later (for development)
import { Template } from 'https://deno.land/x/v3_templater/mod.ts';
const template = new Template();
const result = template.render('Hello {{ name }}!', { name: 'World' });
console.log(result); // "Hello World!"// Import from Deno module
import { Template } from 'https://deno.land/x/v3_templater/mod.ts';
// Create template engine
const template = new Template({
autoEscape: true, // XSS protection by default
cache: true, // LRU caching enabled
strictMode: false, // Fail on undefined variables
});
// Render from string
const result = template.render('Hello {{ name }}!', { name: 'World' });
console.log(result); // "Hello World!"
// Render from file (async)
const html = await template.renderFile('./templates/page.html', {
title: 'My Page',
items: ['foo', 'bar', 'baz']
});{% if user.isAdmin %}
<p>Admin access granted</p>
{% elif user.isEditor %}
<p>Editor access granted</p>
{% else %}
<p>Read-only access</p>
{% endif %}{% for item in items %}
<li>{{ loop.index }}: {{ item }}</li>
{% endfor %}Loop variables:
- loop.index - Current iteration (0-indexed)
- loop.index1 - Current iteration (1-indexed)
- loop.first - True if first iteration
- loop.last - True if last iteration
- loop.length - Total number of items
base.html:
<html>
<head>
<title>{% block title %}Default Title{% endblock %}</title>
</head>
<body>
{% block content %}{% endblock %}
</body>
</html>page.html:
{% extends "base.html" %}
{% block title %}My Page{% endblock %}
{% block content %}
<h1>Hello World!</h1>
{% endblock %}-
upper- Convert to uppercase -
lower- Convert to lowercase -
capitalize- Capitalize first letter -
title- Capitalize each word -
trim- Remove whitespace -
reverse- Reverse string -
truncate(length, suffix)- Truncate to length -
replace(search, replacement)- Replace substring
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length- Get length -
join(separator)- Join elements -
first- Get first element -
last- Get last element -
reverse- Reverse array -
sort(key)- Sort array -
unique- Get unique values -
slice(start, end)- Slice array
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abs- Absolute value -
round- Round number -
floor- Floor number -
ceil- Ceil number -
fixed(decimals)- Fixed decimal places -
percent(decimals)- Format as percentage
const { Template } = require('v3-templater');
const template = new Template({
autoEscape: true, // Auto-escape HTML (default: true)
cache: true, // Enable caching (default: true)
strictMode: false, // Throw on undefined vars (default: false)
delimiters: { // Custom delimiters
start: '{{',
end: '}}'
}
});// Render from string
const result = template.render('Hello {{ name }}', { name: 'World' });
// Render from file
template.setTemplateDirs(['./templates']);
const result = template.renderFile('page.html', { title: 'My Page' });
// Compile for reuse
const compiled = template.compile('Hello {{ name }}');
const result1 = compiled.render({ name: 'Alice' });
const result2 = compiled.render({ name: 'Bob' });template.addFilter('reverse', (value) => {
return value.split('').reverse().join('');
});
template.render('{{ text | reverse }}', { text: 'hello' });
// Output: "olleh"template.addHelper('formatCurrency', (value, currency = 'USD') => {
return new Intl.NumberFormat('en-US', {
style: 'currency',
currency
}).format(value);
});= Basic usage
v3t -t template.html -d data.json
= Output to file
v3t -t template.html -d data.json -o output.html
= Disable auto-escaping
v3t -t template.html -d data.json --no-escape
= Enable strict mode
v3t -t template.html -d data.json --strict
= Show help
v3t --help
= Show version
v3t --versionconst emailTemplate = `
<html>
<body>
<h1>Hello {{ user.name | capitalize }}!</h1>
{% if order %}
<p>Your order #{{ order.id }} has been confirmed.</p>
<h2>Order Details:</h2>
<ul>
{% for item in order.items %}
<li>{{ item.name }} - ${{ item.price | fixed(2) }}</li>
{% endfor %}
</ul>
<p><strong>Total: ${{ order.total | fixed(2) }}</strong></p>
{% endif %}
<p>Thank you for your business!</p>
</body>
</html>
`;
const result = template.render(emailTemplate, {
user: { name: 'john doe' },
order: {
id: 12345,
items: [
{ name: 'Widget', price: 19.99 },
{ name: 'Gadget', price: 29.99 }
],
total: 49.98
}
});const blogTemplate = `
<article>
<h1>{{ post.title }}</h1>
<p class="meta">
By {{ post.author }} on {{ post.date | date('locale') }}
</p>
<div class="content">
{{ post.content }}
</div>
{% if post.tags %}
<div class="tags">
{% for tag in post.tags %}
<span class="tag">{{ tag }}</span>
{% endfor %}
</div>
{% endif %}
<h2>Comments ({{ post.comments | length }})</h2>
{% for comment in post.comments %}
<div class="comment">
<strong>{{ comment.author }}</strong>
<p>{{ comment.text }}</p>
</div>
{% endfor %}
</article>
`;v3-templater takes security seriously:
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Auto-escaping: HTML entities are automatically escaped by default to prevent XSS attacks
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SafeString: Use the
safefilter to mark trusted content -
Strict Mode: Enable strict mode to catch undefined variables
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No Eval: Templates are compiled without using
eval()orFunction()constructor
// Unsafe input is automatically escaped
template.render('{{ userInput }}', {
userInput: '<script>alert("xss")</script>'
});
// Output: <script>alert("xss")</script>
// Mark as safe if you trust the content
template.render('{{ html | safe }}', {
html: '<b>Bold text</b>'
});
// Output: <b>Bold text</b>v3-templater is designed for high performance:
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Compiled Templates: Templates are compiled to optimized JavaScript
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Smart Caching: LRU cache for compiled templates
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Minimal Overhead: Lightweight parser and runtime
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Benchmarks: Run
npm run benchmarkto see performance metrics
Typical performance (on modern hardware): - Simple variables: ~100,000 ops/sec - With caching: ~500,000+ ops/sec - Complex templates: ~50,000 ops/sec
| Feature | v3-templater | Handlebars | EJS | Pug |
|---------|-------------|------------|-----|-----|
| Auto-escaping | ✅ | ✅ | ❌ | ✅ |
| Inheritance | ✅ | Partial | ❌ | ✅ |
| TypeScript | ✅ |
Contributions are welcome! Please read our contributing guidelines and submit pull requests.
v3-templater achieves PLATINUM level compliance with the [Rhodium Standard Repository (RSR) Framework](https://github.com/Hyperpolymath/rhodium-standard-repository) - the highest tier of project quality and governance.
✅ Type Safety: TypeScript strict mode ✅ Memory Safety: Garbage collected (JavaScript/TypeScript) ✅ Documentation: README, API docs, migration guides, contributing guide ✅ License: MIT + Palimpsest v0.8 dual licensing ✅ Security: SECURITY.md, RFC 9116 security.txt ✅ Code of Conduct: Contributor Covenant 2.1 ✅ Maintainers: TPCF Perimeter 3 (Community Sandbox)
✅ .well-known/: security.txt, ai.txt, humans.txt ✅ Build System: npm scripts + justfile + flake.nix ✅ CI/CD: GitHub Actions with comprehensive testing ✅ Tests: 5 test suites, 80%+ coverage enforced ✅ Automation: justfile with 25+ recipes
✅ Nix Flakes: Reproducible builds with flake.nix ✅ Coverage Enforcement: CI fails below 80% threshold ✅ Security Scanning: CodeQL, npm audit automated ✅ Performance: Benchmarks in CI pipeline ✅ RSR Verification: Automated compliance checks
✅ Multi-CI: GitHub Actions + GitLab CI ✅ Container Support: Dockerfile, docker-compose.yml ✅ Dependency Automation: Dependabot + Renovate ✅ SBOM: CycloneDX format, attached to releases ✅ ADRs: Architecture Decision Records ✅ Release Automation: Full automated release workflow ✅ Code Quality Gates: CodeClimate + SonarCloud ✅ OpenSSF Prepared: Best Practices checklist complete ✅ Supply Chain Security: SLSA-aware, vulnerability scanning
Overall Score: 100% (42/42 requirements met)
See [RSR-PLATINUM.md](RSR-PLATINUM.md) for detailed compliance report.
= Using just (recommended)
just rsr-check
= Using script directly
./scripts/verify-rsr.sh
= Using Nix
nix flake checkDual licensed under:
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Palimpsest-MPL-1.0 License - see [LICENSE](LICENSE) file
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Palimpsest License v0.8 - see [LICENSE-PALIMPSEST.txt](LICENSE-PALIMPSEST.txt)
You may choose either license for your use.
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❏ Async template loading
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❏ Streaming support
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❏ Browser build
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❏ More built-in filters
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❏ Template debugging tools
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❏ Performance optimizations
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❏ Macro support
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❏ i18n integration
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📖 [Documentation](https://github.com/Hyperpolymath/v3-templater#readme)
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🐛 [Issue Tracker](https://github.com/Hyperpolymath/v3-templater/issues)
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💬 [Discussions](https://github.com/Hyperpolymath/v3-templater/discussions)
