Safari Internal JavaScript Services

Safari Version:** 15.7
Extraction Method:** dyld_shared_cache
Extraction Date:** 16/01/2026

Disclaimer:

These files are provided for educational and research purposes only. They are extracted from Safari's internal implementation to help developers and researchers understand browser functionality. These files are property of Apple Inc. and should not be used in production environments or for any commercial purposes.

Note: The summaries and descriptions of each file below were AI-generated and may contain inaccuracies or inconsistencies.

Password & Form Autofill System

AutomaticPasswords.js

Manages Safari's automatic strong password generation:

Removes auto-generated passwords from password fields
Controls visibility of suggested strong passwords
Handles focus/blur events when users interact with password fields
Manages the "autofilled" state of password inputs

FormMetadata.js

The brain of Safari's form autofill system:

Form Detection & Classification: Identifies login forms, signup forms, password change forms, and standard forms
Smart Field Recognition: Uses pattern matching, element positioning, visual analysis, and machine learning-like scoring to identify:
- Username fields
- Password fields (current, new, confirm)
- Credit card fields (number, CVV, expiration, cardholder)
- Address fields (street, city, postal code)
- Phone numbers (split across multiple fields)
- Email addresses
- One-time codes (2FA)

FormMetadataClassification.js

Intelligently classifies form fields to enable autofill:

Identifies field types: credit cards, names, addresses, phone numbers, emails, birthdays, passwords, etc.
Handles multi-part fields: splits fields like "First Name | Last Name" or phone numbers across multiple inputs
Continuation detection: recognizes when a single piece of data (like credit card number) is split across multiple fields
Uses multiple signals: autocomplete attributes, field names, placeholders, sizes, and positioning
Date field parsing: understands various date formats and splits (day/month/year)
Smart matching: uses pattern recognition to classify fields even without explicit HTML hints

NodePath.js

Creates stable references to DOM elements:

Path-based element identification: creates a "fingerprint" for DOM nodes that works even when the DOM changes
Fuzzy matching: uses similarity scoring (Levenshtein distance) to relocate elements after page updates
Handles shadow DOM and iframes: traverses across shadow boundaries and iframe documents
Range support: can reference text selections, not just elements
Resilient resolution: uses multiple strategies (CSS selectors, position, attributes) to find elements

Reader Mode System

Reader.js

Powers Safari's Reader Mode core functionality:

Manages visibility transitions for Reader view
Handles iframe URL caching/restoration when entering/exiting Reader
Checks JavaScript enablement settings
Mac-specific UI adjustments

ReaderArticleFinder.js (~3500 lines)

Safari's article detection and cleaning algorithm (similar to Mozilla's Readability):

Article Detection Strategies:

Schema.org metadata (<article itemtype="Article">)
OpenGraph tags (<meta property="og:type" content="article">)
Visual examination (hit-testing specific screen coordinates)
Quirks list for known sites (NYTimes, Medium, etc.)

Scoring System:

Text density analysis
Link density (fewer links = more likely article)
Tag names (article, main, section boost score)
Class names ("article", "content" boost; "comment", "sidebar" reduce)
Position on page
Font consistency

Smart Cleaning:

Removes ads, comments, navigation
Keeps images, videos, tweets
Converts lazy-loaded images
Preserves tables and code blocks
Handles multi-column layouts
Detects CJK (Chinese, Japanese, Korean) text using Unicode ranges

ReaderSharedUI.js

Powers the actual Reader Mode interface:

Layout Management:

Multi-column pagination for long articles
Responsive design adapting to window size
12+ font families (System, Charter, Georgia, Iowan, Palatino, etc.)
4 themes: White, Sepia, Gray, Night
12 text size levels with custom line heights per font

Interactive Features:

Smooth scrolling with animations
Content-aware navigation (stops at natural break points)
Next page auto-loading for paginated articles
Print/email formatting
Reading position memory
Table of Contents generation from headings
AI-generated summary display with collapsible UI
Sidebar for TOC/summary on wide screens

ReaderSharedUINormalWorld.js

Enhances Reader Mode with rich content:

Twitter/X integration: replaces simple tweet embeds with rich Twitter widgets
Loads Twitter's widget JavaScript on demand
Handles transition from placeholder tweets to interactive embeds