JavaScript Templating: From Server to Browser

The evolution of JavaScript templating has been fascinating to watch. From server-side rendering with PHP includes to modern JSX, each generation of templating solutions has solved different problems while introducing new challenges.

The Browser-Native Gap

While server-side templating matured with systems like Django Templates and Jinja, browser-native templating lagged behind. This gap led me to create `genie`—a templating library designed specifically for browser environments.

Design Principles

Familiar Syntax

Genie adopts Django/Jinja-style syntax because it's proven to be both powerful and readable:

var template = new Template("Hello [[name]], you have [[count]] messages.");
var result = template.render({
    name: 'Graham',
    count: 5
});

Error Handling

Unlike many templating systems, Genie provides detailed error information:

try {
    template.render(data);
} catch (error) {
    console.log(error.line, error.column, error.context);
}

Performance Considerations

Browser templating needs to be fast. Genie compiles templates to JavaScript functions for optimal execution speed:

// Compiled template (simplified)
function(context) {
    return "Hello " + context.name + ", you have " + context.count + " messages.";
}

Modern Context

While React and other frameworks have largely solved the templating problem for application development, there's still a place for lightweight, dependency-free templating libraries in certain contexts:

• Browser extensions
• Embedded widgets
• Legacy system integration
• Learning environments

The key is choosing the right tool for the specific problem you're solving.