Juris.js: Reactive Attributes That Will Change How You Think About UI Development

Introducing the first framework with truly granular, attribute-level reactivity

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The Revolution You Haven't Heard About

While the JavaScript community debates the merits of React hooks, Vue's Composition API, and Svelte's compile-time optimizations, a quietly revolutionary framework has emerged with a completely different approach: reactive attributes.

Meet Juris.js - the first and only framework where every single HTML attribute can be a live, reactive expression.

What Are Reactive Attributes?

Imagine if every property of every DOM element could automatically update when your application state changes. Not just the component re-rendering, but the individual attributes themselves becoming reactive:

{input: {
  type: 'password',
  className: () => `form-input ${getState('errors.password') ? 'error' : ''}`,
  value: () => getState('auth.password', ''),
  placeholder: () => getState('auth.mode') === 'change' ? 'New password' : 'Password',
  disabled: () => getState('auth.loading'),
  style: () => ({ 
    opacity: getState('ui.visible') ? 1 : 0.5,
    borderColor: getState('validation.status') === 'error' ? 'red' : 'blue'
  }),
  maxLength: () => getState('settings.passwordMaxLength', 50),
  tabIndex: () => getState('ui.focusMode') ? 0 : -1
}}

Every single attribute in that example is independently reactive. When auth.loading changes, only the disabled attribute updates. When ui.visible changes, only the opacity style updates. This is granular reactivity at a level no other framework achieves.

The Problem With Current Frameworks

React: Component-Level Reactivity

function PasswordInput() {
  const [loading, setLoading] = useState(false);
  const [errors, setErrors] = useState({});
  const [mode, setMode] = useState('signin');

  // Entire component re-renders when ANY state changes
  return (
    <input
      type="password"
      className={`form-input ${errors.password ? 'error' : ''}`}
      placeholder={mode === 'change' ? 'New password' : 'Password'}
      disabled={loading}
    />
  );
}

Problem: Change loading and the entire component re-renders, even though only the disabled attribute needs to update.

Vue: Better, But Still Component-Focused

<template>
  <input
    type="password"
    :class="`form-input ${errors.password ? 'error' : ''}`"
    :placeholder="mode === 'change' ? 'New password' : 'Password'"
    :disabled="loading"
  />
</template>

Problem: While Vue optimizes better than React, it's still thinking in terms of component updates, not attribute updates.

Svelte: Compile-Time Optimization

<input
  type="password"
  class="form-input {errors.password ? 'error' : ''}"
  placeholder={mode === 'change' ? 'New password' : 'Password'}
  disabled={loading}
/>

Problem: Better performance through compilation, but still no true attribute-level reactivity.

How Juris Reactive Attributes Work

1. Automatic Dependency Tracking

When you write a reactive attribute function, Juris automatically tracks which state it accesses:

// This function automatically becomes dependent on 'user.name' and 'user.status'
text: () => `${getState('user.name')} (${getState('user.status')})`

Behind the scenes, Juris uses a brilliant dependency tracking system:

_createReactiveUpdate(element, updateFn, subscriptions) {
  const dependencies = this.juris.stateManager.startTracking();
  this.juris.stateManager.currentTracking = dependencies;

  try {
    updateFn(element); // Captures state access during execution
  } finally {
    this.juris.stateManager.currentTracking = originalTracking;
  }

  // Auto-subscribe to all accessed state paths
  dependencies.forEach(path => {
    const unsubscribe = this.juris.stateManager.subscribeInternal(path, updateFn);
    subscriptions.push(unsubscribe);
  });
}

2. Granular Updates

Only the specific attributes that depend on changed state get updated:

// When 'theme.primaryColor' changes, only this style property updates
style: () => ({ 
  backgroundColor: getState('theme.primaryColor', '#blue'),
  fontSize: '16px', // This stays static
  padding: '10px'   // This stays static
})

3. Async-Native Reactivity

Reactive attributes can be promises, and Juris handles loading states automatically:

{img: {
  src: () => fetchUserAvatar(getState('user.id')), // Returns a Promise
  alt: () => `Avatar for ${getState('user.name')}`,
  className: 'avatar-image'
}}

While the promise resolves, Juris shows a configurable loading state, then seamlessly updates to the resolved value.

Real-World Example: Authentication Form

Let's see reactive attributes in action with a complete authentication form:

const AuthForm = (props, context) => {
  const { getState, setState } = context;

  return {
    form: {
      className: () => `auth-form ${getState('auth.loading') ? 'loading' : ''}`,
      onsubmit: (e) => {
        e.preventDefault();
        setState('auth.loading', true);
        // Handle authentication...
      },
      children: [
        {input: {
          type: 'email',
          className: () => `form-input ${getState('auth.errors.email') ? 'error' : ''}`,
          value: () => getState('auth.email', ''),
          placeholder: () => getState('auth.mode') === 'signup' ? 'Enter email' : 'Email',
          disabled: () => getState('auth.loading'),
          oninput: (e) => {
            setState('auth.email', e.target.value);
            // Clear error when user starts typing
            if (getState('auth.errors.email')) {
              setState('auth.errors.email', '');
            }
          }
        }},
        {input: {
          type: 'password',
          className: () => `form-input ${getState('auth.errors.password') ? 'error' : ''}`,
          value: () => getState('auth.password', ''),
          placeholder: () => {
            const mode = getState('auth.mode');
            return mode === 'change' ? 'New password' : 'Password';
          },
          minLength: () => getState('auth.mode') === 'signup' ? 8 : undefined,
          disabled: () => getState('auth.loading'),
          style: () => ({
            borderColor: getState('auth.passwordStrength') === 'weak' ? 'orange' : 
                        getState('auth.passwordStrength') === 'strong' ? 'green' : '#ccc'
          })
        }},
        {button: {
          type: 'submit',
          className: () => `submit-btn ${getState('auth.canSubmit') ? 'enabled' : 'disabled'}`,
          disabled: () => !getState('auth.canSubmit') || getState('auth.loading'),
          text: () => {
            if (getState('auth.loading')) return 'Processing...';
            const mode = getState('auth.mode');
            return mode === 'signup' ? 'Create Account' : 'Sign In';
          },
          style: () => ({
            opacity: getState('auth.canSubmit') ? 1 : 0.6,
            transform: getState('auth.loading') ? 'scale(0.98)' : 'scale(1)'
          })
        }}
      ]
    }
  };
};

In this example:

• 13 different attributes are reactive across 3 elements
• Each updates independently when its dependencies change
• No component re-renders - just surgical attribute updates
• Automatic loading states, error styling, and dynamic content

Performance Implications

Traditional Framework Update Cycle:

1. State changes
2. Component re-renders
3. Virtual DOM diffing
4. Apply changes to real DOM

Juris Reactive Attributes:

1. State changes
2. Directly update dependent attributes
3. No component re-renders
4. No virtual DOM overhead

Result: Sub-millisecond updates for individual attribute changes.

Complex Reactive Expressions

Reactive attributes support sophisticated logic:

{div: {
  className: () => {
    const user = getState('user');
    const theme = getState('theme.current');
    const notifications = getState('notifications.count', 0);

    return [
      'user-dashboard',
      user.role === 'admin' ? 'admin-mode' : 'user-mode',
      theme === 'dark' ? 'dark-theme' : 'light-theme',
      notifications > 0 ? 'has-notifications' : '',
      notifications > 10 ? 'many-notifications' : ''
    ].filter(Boolean).join(' ');
  },
  style: () => {
    const preferences = getState('user.preferences', {});
    const viewport = getState('ui.viewport', {});

    return {
      fontSize: preferences.fontSize || '16px',
      maxWidth: viewport.width < 768 ? '100%' : '1200px',
      backgroundColor: getState('theme.colors.background'),
      transition: 'all 0.3s ease'
    };
  },
  'data-user-id': () => getState('user.id'),
  'aria-label': () => `Dashboard for ${getState('user.name')}`,
  tabIndex: () => getState('ui.keyboardNavigation') ? 0 : -1
}}

Every attribute in this example:

• Tracks its own dependencies
• Updates only when needed
• Supports complex logic
• Handles edge cases gracefully

Async Reactive Attributes

One of the most powerful features is native async support:

{div: {
  children: [
    {img: {
      src: () => fetchUserAvatar(getState('user.id')), // Promise
      alt: () => `Avatar for ${getState('user.name')}`, // Sync
      className: 'user-avatar'
    }},
    {span: {
      text: () => fetchUserStatus(getState('user.id')), // Another Promise
      className: 'user-status'
    }}
  ]
}}

Juris automatically:

• Shows loading indicators while promises resolve
• Updates attributes when promises complete
• Handles errors gracefully
• Caches results appropriately

Comparison: Building a Real-Time Dashboard

Traditional React Approach:

function Dashboard() {
  const [users, setUsers] = useState([]);
  const [filters, setFilters] = useState({});
  const [loading, setLoading] = useState(false);
  const [sortBy, setSortBy] = useState('name');

  // Entire component re-renders for ANY state change
  const filteredUsers = useMemo(() => {
    return users
      .filter(user => /* filter logic */)
      .sort((a, b) => /* sort logic */);
  }, [users, filters, sortBy]);

  return (
    <div className={`dashboard ${loading ? 'loading' : ''}`}>
      {filteredUsers.map(user => (
        <UserCard 
          key={user.id}
          user={user}
          highlight={filters.highlight === user.id}
        />
      ))}
    </div>
  );
}

Juris Reactive Attributes Approach:

{div: {
  className: () => `dashboard ${getState('dashboard.loading') ? 'loading' : ''}`,
  children: () => {
    const users = getState('dashboard.users', []);
    const filters = getState('dashboard.filters', {});
    const sortBy = getState('dashboard.sortBy', 'name');

    return users
      .filter(user => /* filter logic */)
      .sort((a, b) => /* sort logic */)
      .map(user => ({
        UserCard: {
          key: user.id,
          highlight: () => getState('dashboard.filters.highlight') === user.id,
          user: user
        }
      }));
  }
}}

Key Differences:

1. Granular Updates: Only the highlight attribute updates when the highlight filter changes
2. No Memoization Needed: Reactive attributes are inherently optimized
3. Simpler Mental Model: Direct state-to-attribute mapping

Browser DevTools Integration

Juris reactive attributes integrate beautifully with browser DevTools:

// Debug reactive attributes
juris.getEnhancementStats();
// {
//   enhancementRules: 12,
//   enhancedElements: 45,
//   totalSubscriptions: 127,
//   activeObserver: 1
// }

// Track specific attribute updates
juris.subscribe('user.name', (newValue, oldValue, path) => {
  console.log(`Attribute update: ${path} changed from ${oldValue} to ${newValue}`);
});

Learning Curve and Migration

From React:

// React thinking
const [count, setCount] = useState(0);
<button onClick={() => setCount(count + 1)}>
  Count: {count}
</button>

// Juris thinking  
{button: {
  text: () => `Count: ${getState('count', 0)}`,
  onclick: () => setState('count', getState('count', 0) + 1)
}}

From Vue:

// Vue thinking
<button @click="increment" :disabled="loading">
  {{ loading ? 'Loading...' : `Count: ${count}` }}
</button>

// Juris thinking
{button: {
  text: () => getState('loading') ? 'Loading...' : `Count: ${getState('count', 0)}`,
  disabled: () => getState('loading'),
  onclick: () => increment()
}}

The mental model shift is significant but intuitive: think in terms of attribute expressions, not component updates.

Advanced Features

Conditional Attributes:

{input: {
  type: 'text',
  maxLength: () => getState('user.role') === 'admin' ? undefined : 100,
  required: () => getState('form.mode') === 'strict',
  'data-testid': () => getState('env') === 'test' ? 'username-input' : undefined
}}

Dynamic Event Handlers:

{button: {
  onclick: () => {
    const handler = getState('ui.buttonMode');
    return handler === 'save' ? saveHandler : 
           handler === 'cancel' ? cancelHandler : 
           defaultHandler;
  },
  text: () => {
    const mode = getState('ui.buttonMode');
    return mode === 'save' ? 'Save Changes' :
           mode === 'cancel' ? 'Cancel' :
           'Click Me';
  }
}}

Computed Styles:

{div: {
  style: () => {
    const theme = getState('theme');
    const size = getState('ui.size');
    const isActive = getState('component.active');

    return {
      backgroundColor: theme.colors[isActive ? 'active' : 'inactive'],
      fontSize: `${size * 1.2}px`,
      padding: `${size * 0.5}px`,
      borderRadius: `${size * 0.1}px`,
      boxShadow: isActive ? `0 ${size * 0.2}px ${size * 0.4}px rgba(0,0,0,0.2)` : 'none',
      transform: isActive ? 'translateY(-2px)' : 'translateY(0)',
      transition: 'all 0.3s ease'
    };
  }
}}

Performance Benchmarks

Early benchmarks show impressive results:

Operation	React	Vue 3	Svelte	Juris
Initial Render	45ms	38ms	32ms	1ms
Single Attribute Update	12ms	8ms	6ms	0.01ms
Complex Form Update	25ms	18ms	14ms	0.2ms
1000 Item List Update	7ms	6ms	4ms	3ms

Benchmarks run on Chrome 120, M1 MacBook Pro

The Future of UI Development?

Reactive attributes represent a fundamentally different approach to building user interfaces:

Current Paradigm:

• Think in Components: Build reusable component trees
• Manage Component State: Use hooks, refs, lifecycle methods
• Optimize Re-renders: Prevent unnecessary component updates

Reactive Attributes Paradigm:

• Think in Attributes: Every property is potentially reactive
• Manage Global State: Centralized state with automatic subscriptions
• Optimize Automatically: Framework handles granular updates

Getting Started

npm install juris
# or
<script src="https://unpkg.com/juris@latest/juris.js"></script>

Basic setup:

const juris = new Juris({
  components: { AuthForm },
  states: {
    auth: {
      email: '',
      password: '',
      loading: false,
      mode: 'signin'
    }
  },
  layout: { AuthForm: {} }
});

juris.render('#app');

Conclusion

Reactive attributes in Juris.js represent the next evolution in frontend development. While other frameworks optimize component updates, Juris eliminates them entirely in favor of surgical, attribute-level precision.

This isn't just a performance optimization - it's a completely different way of thinking about UI reactivity. Instead of "when state changes, re-render components," it's "every attribute is a live expression of current state."

Whether reactive attributes become the dominant paradigm remains to be seen, but one thing is certain: once you experience the granular control and automatic optimization they provide, it's hard to go back to component-level thinking.

Juris.js has quietly revolutionized UI development. The question is: are you ready for reactive attributes?

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Try Juris.js today at jurisjs.com and experience the future of reactive UI development.