dars-framework 1.3.9

Dars is a Python UI framework for building modern, interactive web apps with only Python code. Write your interface in Python, export it to static HTML/CSS/JS, and deploy anywhere.

Dars Framework

Dars is a multiplatform Python UI framework for building modern, interactive web and desktop apps with Python code. Write your interface in Python, export it to web technologies and deploy anywhere.

Official Website | Documentation Docs | DeepWiki here |

pip install dars-framework

Some Javascript and css stack required for advanced personalization.

Try dars without installing nothing just visit the Dars Playground

How It Works

• Build your UI using Python classes and components (like Text, Button, Container, Page, etc).
• Preview instantly with hot-reload using app.rTimeCompile().
• Export your app to static web files with a single CLI command.
• Export to native desktop apps (BETA) using project config format: "desktop" and dars build.
• Use multipage, layouts, scripts, and more—see docs for advanced features.
• For more information visit the Documentation

Quick Example: Your First App

from dars.all import *

app = App(title="Hello World", theme="dark")
# Crear componentes
index = Page(
     Text(
        text="Hello World",
        style={
            'font-size': '48px',
            'color': '#2c3e50',
            'margin-bottom': '20px',
            'font-weight': 'bold',
            'text-align': 'center'
        }
    ),
    Text(
        text="Hello World",
        style={
            'font-size': '20px',
            'color': '#7f8c8d',
            'margin-bottom': '40px',
            'text-align': 'center'
        }
    ),

    Button(
        text="Click Me!",
        on_click= dScript("alert('Hello World')"),
        style={
            'background-color': '#3498db',
            'color': 'white',
            'padding': '15px 30px',
            'border': 'none',
            'border-radius': '8px',
            'font-size': '18px',
            'cursor': 'pointer',
            'transition': 'background-color 0.3s'
        }
    ),
    style={
        'display': 'flex',
        'flex-direction': 'column',
        'align-items': 'center',
        'justify-content': 'center',
        'min-height': '100vh',
        'background-color': '#f0f2f5',
        'font-family': 'Arial, sans-serif'
    }
) 

app.add_page("index", index, title="Hello World", index=True)

if __name__ == "__main__":
    app.rTimeCompile()

---

Reactivity and State System

Dars Framework includes a built-in reactive state system (dState / cState) that allows dynamic and modular DOM updates directly from Python. It enables fully event-driven interfaces without requiring manual JavaScript.

Key Concepts

• dState(name, component, states) Creates a reactive state controller bound to a specific component and a list of possible states.

• cState(idx, mods=[...]) Defines rules (modifications) that are automatically applied when entering a specific state.

• Mod Helpers A compact way to modify DOM elements on state changes: inc, dec, set, toggle_class, append_text, prepend_text, goto, and more.

• Deferred Mutations Using component.attr(..., defer=True) or component.mod(...) inside a cComp=True state defers HTML updates until an event occurs, preventing authoring-time mutations.

Example Template

A complete example demonstrating dState, cState, Mod, and deferred updates is available here

Features

• Reactive Mod system with compact Mod helpers
• Unified event model — any component can use on_* props (on_click, on_input, on_change, etc.)
• Deferred rendering for safer, predictable state transitions (cComp=True)
• Navigation between states using goto, including relative moves ('+1', '-1')
• Consistent, event-time mutation flow for reliable behavior
• Secure minification for production bundles (strong JS/CSS minifier integrated into the build pipeline)

Dynamic State Updates with this()

The this() helper enables direct, event-time component updates without pre-defining states:

from dars.all import *

counter = Text("0", id="count")
btn = Button("Increment", on_click=this().state(text=Mod.inc("count")))

# Use RawJS for dynamic values (e.g., from async operations)
from dars.desktop import read_text

display = Text("", id="display")
read_btn = Button("Load", on_click=read_text("data.txt").then(
    this().state(text=RawJS(dScript.ARG))  # Update with file content
))

• Works anywhere: desktop and web exports
• Perfect for async operations and chained scripts
• Combines with dScript.then() for sequencing

---

CLI Usage

Command	What it does
dars export my_app.py --format html	Export app to HTML/CSS/JS in ./my_app_web
dars init --type desktop	Scaffold desktop-capable project (BETA)
dars build (desktop config)	Build desktop app artifacts (BETA)
dars preview ./my_app_web	Preview exported app locally
dars init my_project	Create a new Dars project (also creates dars.config.json)
dars init --update	Create/Update dars.config.json in current dir
dars build	Build using dars.config.json (entry/outdir/format)
dars config validate	Validate dars.config.json and print report
dars info my_app.py	Show info about your app
dars formats	List supported export formats
dars --help	Show help and all CLI options

Tip: use dars doctor to review optional tooling that can enhance bundling/minification.

Desktop Export (BETA)

• Mark your project for desktop in dars.config.json with "format": "desktop".
• Initialize backend scaffolding with dars init --type desktop (or --update).
• Build with dars build to produce desktop artifacts under dist/.
• This feature is in BETA: usable for testing, not yet recommended for production.

More

• Visit dars official website
• Visit the dars official Documentation now on separate website.
• Try dars without installing nothing just visit the Dars Playground

Local Execution and Live Preview

To test your app locally before exporting, use the hot-reload preview from any Python file that defines your app:

if __name__ == "__main__":
    app.rTimeCompile()

Then run your file directly:

python my_app.py

This will start a local server at http://localhost:8000 so you can view your app in the browser—no manual export needed. You can change the port with:

python my_app.py --port 8088

---

You can also use the CLI preview command on an exported app:

dars preview ./my_exported_app

This will start a local server at http://localhost:8000 to view your exported app in the browser.

---

Project Configuration (dars.config.json)

Dars can read build/export settings from a dars.config.json at your project root. It is created automatically by dars init, and you can add it to existing projects with dars init --update.

Example default:

{
  "entry": "main.py",
  "format": "html",
  "outdir": "dist",
  "publicDir": null,
  "include": [],
  "exclude": ["**/__pycache__", ".git", ".venv", "node_modules"],
  "bundle": true,
  "defaultMinify": true,
  "viteMinify": true
}

• entry: Python entry file. Used by dars build and dars export config.
• format: Export format. Currently only html is supported.
• outdir: Output directory. Used by dars build and default for dars export when not overridden.
• publicDir: Folder (e.g., public/ or assets/) copied into the output. If null, it is autodetected.
• include/exclude: Basic filters for copying from publicDir.
• bundle: Reserved for future use. CLI exports and build already bundle appropriately.
• defaultMinify: Toggle the built-in Python minifier (safe, conservatively preserves <pre>, <code>, script, style, textarea). Controls HTML minification and provides JS/CSS fallback when advanced tools are unavailable. Default true.
• viteMinify: Toggle the Vite/esbuild minifier for JS/CSS. Default true.

Validate your config:

dars config validate

Build using config:

dars build

Export using the config entry and outdir:

dars export config --format html

---

See LandingPage docs for details: state_management.md, events.md, scripts.md.

More

• Visit dars official website
• Visit the dars official Documentation now on separate website.
• Try dars without installing nothing just visit the Dars Playground

Local Execution and Live Preview

To test your app locally before exporting, use the hot-reload preview from any Python file that defines your app:

if __name__ == "__main__":
    app.rTimeCompile()

Then run your file directly:

python my_app.py

This will start a local server at http://localhost:8000 so you can view your app in the browser—no manual export needed. You can change the port with:

python my_app.py --port 8088

---

You can also use the CLI preview command on an exported app:

dars preview ./my_exported_app

This will start a local server at http://localhost:8000 to view your exported app in the browser.