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https://github.com/amirfarzamnia/templon

Advanced template compiler with deep variable resolution, object processing, and strict validation with circular reference protection.
https://github.com/amirfarzamnia/templon

complier deep interpolation nested object string substitution template variable

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Advanced template compiler with deep variable resolution, object processing, and strict validation with circular reference protection.

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# Templon

Advanced template compiler with deep variable resolution, object processing, and strict validation with circular reference protection.



Templon


[![npm version](https://badge.fury.io/js/templon.svg)](https://www.npmjs.com/package/templon)
[![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://opensource.org/licenses/MIT)
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## Features

- **Deep Variable Resolution**: Access nested properties using dot notation (e.g., `{{user.profile.name}}`)
- **Object/Array Processing**: Automatically handle complex data structures
- **Strict Mode**: Validate template variables and throw errors for missing values
- **Custom Resolvers**: Extend functionality with custom variable resolution logic
- **Circular Reference Protection**: Prevent infinite loops with depth limiting
- **TypeScript Support**: Full type safety and autocompletion
- **Customizable Variable Pattern**: Use your own regex pattern for variable matching

## Installation

```bash
npm install templon
# or
yarn add templon
# or
pnpm add templon
```

## Basic Usage

```typescript
import { compileTemplate } from "templon";

// Simple string interpolation
const result = compileTemplate("Hello {{name}}", { name: "World" });
// Output: "Hello World"

// Nested object access
const result = compileTemplate("Hello {{user.profile.name}}", {
user: {
profile: {
name: "John",
},
},
});
// Output: "Hello John"

// Array access
const result = compileTemplate("First user: {{users.0.name}}", {
users: [{ name: "John" }, { name: "Jane" }],
});
// Output: "First user: John"
```

Note: The template engine uses [radash](https://radash-docs.vercel.app/docs/object/get) under the hood for deep property access, which provides safe and efficient object traversal.

## Advanced Examples

### Working with Arrays

```typescript
const template = "Users: {{users}}";
const data = {
users: ["John", "Jane", "Bob"],
};
const result = compileTemplate(template, data);
// Output: "Users: John,Jane,Bob"
```

### Custom Variable Pattern

```typescript
const template = "Hello ";
const result = compileTemplate(
template,
{ name: "World" },
{ variablePattern: /<([^{}]+)>/g }
);
// Output: "Hello World"
```

### Strict Mode

```typescript
const template = "Hello {{name}}";

try {
compileTemplate(template, {}, { strict: true });
} catch (error) {
// Error: Missing variable: name
}
```

### Custom Resolver

```typescript
const template = "Hello {{user.name}}";
const result = compileTemplate(
template,
{},
{
resolver: (path) => {
if (path === "user.name") return "Custom User";

return undefined;
},
}
);
// Output: "Hello Custom User"
```

## Configuration Options

| Option | Type | Default | Description |
| -------------------- | ------------------------- | --------------- | ------------------------------------------ |
| strict | boolean | false | Throw errors when variables are missing |
| preserveUndefined | boolean | false | Preserve undefined variables in output |
| autoStringifyObjects | boolean | true | Automatically stringify objects to JSON |
| parseStrings | boolean | true | Automatically parse strings in output |
| parseBinInts | boolean | false | Automatically parse BigInts in output |
| resolver | (path: string) => any | undefined | Custom variable resolver function |
| stringTransform | (value: string) => string | (s) => s | Transform function for final string output |
| maxVariableDepth | number | 10 | Maximum depth for variable resolution |
| variablePattern | RegExp | /{{([^{}]+)}}/g | Custom regex pattern for variable matching |

## Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

## License

This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.