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Published Nov 6, 2023 ⦁ 9 min read

Safari Dev Tools: The Complete 2023 Guide

Introduction to Safari Developer Tools

Safari is Apple's proprietary web browser that comes pre-installed on all Mac and iOS devices. Its integrated developer tools provide everything web developers need to build, debug and optimize websites for Apple's ecosystem.

In this comprehensive tutorial, we'll cover key capabilities of Safari's dev tools including:

  • The Web Inspector for inspecting page structure and CSS
  • The Debugger for stepping through JavaScript code
  • The Resources panel for auditing page assets
  • The Audits panel for testing web standards compliance
  • Device Mode for simulating mobile screens
  • Advanced debugging features like conditional breakpoints
  • Network throttling to simulate real-world conditions
  • Experimental features for early access

By the end, you'll have master expertise using Safari dev tools to squash bugs faster, improve site performance, and deliver exceptional web experiences across Apple devices. You'll also discover resources like DevHunt to continue exploring the latest Safari developer tools.

A Brief History of Safari

Safari originated within Apple in 2003, based on the open source KHTML rendering engine. It was first released for Mac OS X Panther and quickly became Apple's default browser.

In 2007, Apple launched the first Windows version of Safari to expand its userbase. That same year, Safari made its mobile debut on the first iPhone.

Over the years, Safari has gone through many major version updates adding new features and support for emerging web standards. It remains the pre-installed browser on all Apple operating systems and devices including Macs, iPhones and iPads.

Why Learn Safari Developer Tools?

Here are some key reasons web developers should learn Safari dev tools:

  • Pre-installed on all Mac and iOS devices, used by millions globally
  • Allows direct debugging on iOS devices
  • Can emulate mobile devices in desktop browser
  • Essential for targeting Apple's ecosystem
  • Identify optimizations for Safari to improve site experience
  • Learn how your sites perform on Safari and make improvements
  • Fix rendering issues specific to WebKit browser engine
  • Utilize experimental features to build cutting-edge websites
  • Discover new Safari dev tools on platforms like DevHunt

With Safari holding significant browser market share, especially in the mobile space, having expertise in its developer tools is vital for crafting high-quality cross-browser experiences.

Core Safari Developer Tools

Now let's dive into the core developer tools available within Safari on both desktop and mobile.

The Web Inspector

The Web Inspector is the main hub for visually inspecting and modifying a web page. Key functions include:

  • View and edit the live DOM tree
  • Inspect and modify CSS styles
  • Audit accessibility information
  • Analyze network requests and performance
  • Identify layout issues or style problems
  • Live edit code changes right in the browser

For front-end developers, the Inspector is indispensable for debugging HTML, CSS and accessibility issues. You can instantly see how changes to markup and styles affect rendering.

The Debugger

Safari's JavaScript Debugger allows pausing code execution to step through scripts line-by-line. You can:

  • Set breakpoints to isolate issues
  • Inspect stack traces and variable scopes
  • Profile memory usage and CPU utilization
  • Emulate device throttling conditions
  • Blackbox third-party scripts

The Debugger equips you to tackle even the most complex JavaScript bugs. From tracking down logic errors to profiling performance, it's an essential tool for front-end logic and optimization.

The Resources Panel

This panel displays all resources loaded by the page like scripts, stylesheets, fonts, images and media. For each resource you can:

  • View request URLs, status codes and timings
  • Filter by type, folder location or domain
  • Check dependencies and redundancy
  • Audit performance and bottlenecks
  • Download resources to your machine

Knowing exactly what resources a page loads is invaluable for optimizing performance. The Resources panel helps you eliminate unnecessary requests and prioritize critical assets.

Storage Inspector

The Storage Inspector lets you view and edit browser storage like cookies, LocalStorage, SessionStorage and IndexedDB. You can:

  • Add, modify or delete stored keys and values
  • Export storage data as JSON
  • Emulate different browser states for testing
  • Clear storage entirely to test initial experience

Being able to inspect persistence mechanisms is vital for debugging issues related to state management in modern web apps.

The Audits Panel

Safari's Audits panel runs diagnostics on pages to surface optimization opportunities and standards compliance issues. Audits include:

  • Performance analysis and scoring
  • Accessibility checks following WCAG guidelines
  • Best practices for progressive web apps
  • SEO enhancements
  • Modern web platform usage

Running audits before launching any website can help you catch critical problems early and compare against industry benchmarks.

Advanced Safari Developer Tools

Beyond the basics, Safari offers powerful advanced tools for seasoned developers.

Device Mode

Device Mode accurately emulates mobile screens and conditions right in desktop Safari:

  • Simulate precise device dimensions and resolution
  • Throttle CPU and network to mimic real devices
  • Essential for building mobile-friendly, responsive sites
  • Test touch events and gestures during development

With Device Mode, you can build fully optimized mobile experiences without constantly switching devices.

Advanced Debugging

Safari provides next-level JavaScript debugging capabilities:

  • Set conditional breakpoints using expressions
  • Group breakpoints for easy management
  • Step through async code with async stack traces
  • Profile memory heap allocations over time
  • Blackbox scripts to hide library code
  • Break on caught or uncaught exceptions

These advanced features help you tackle difficult bugs in even the most complex single-page apps and frameworks like Vue.js.

Network Throttling

Network Throttling allows simulating slow network connections, like 3G and LTE. You can:

  • Rate limit bandwidth and latency
  • Identify assets blocking page load
  • Debug loading behavior in emerging markets
  • Optimize performance for offline/low-bandwidth
  • Throttle cache usage and response compression

Testing how your site performs under real-world network conditions is crucial to providing good user experiences for all.

Experimental Features

Safari lets developers try out experimental tools before they are formally released:

  • Get early access to new capabilities
  • Provide feedback to help shape future features
  • Use at your own risk as they are still in development
  • Currently includes CSS Flexbox debugging tools

Tapping into experimental features allows you to build cutting-edge experiences and directly influence the browser platform's evolution.

Debugging JavaScript Issues

Now let's explore strategies for debugging JavaScript using Safari's advanced capabilities.

Breakpoint Usage

Effective breakpoint usage is key for isolating issues:

  • Set breakpoints directly within the source code
  • Organize breakpoints into groups by context
  • Use conditional breakpoints to pause on specific criteria
  • Disable breakpoints without deleting to toggle behavior
  • Manage breakpoints efficiently even in complex codebases

Mastering breakpoints gives you precise control over pausing execution to inspect logic flow and data.

Scope Inspection

Understanding scope is vital for tracking down variable issues:

  • Inspect variable values in different call frames
  • Detect scope pollution across closures and modules
  • Ensure code executes in the intended lexical scope
  • Fix bugs caused by accessing stale variable references
  • Avoid global namespace pollution

With Safari's scoping tools, you can confidently debug even complex nested closures and callback contexts.

Async Debugging

Safari provides multiple approaches for debugging asynchronous code:

  • Step through promise resolutions and rejections
  • Inspect async operation call stacks and task queues
  • Profile async code performance with CPU profiler
  • Set breakpoints within async callbacks and timers
  • Visually trace async code flows

Smooth async debugging helps you tackle race conditions, timing issues, and callback hell.

Error Handling

The key to debugging runtime errors is Safari's break on exception feature:

  • Break on any caught or uncaught exceptions
  • Inspect error call stacks to trace where issues originate
  • Log values with console.log() to debug logic flow
  • Validate edge cases and fix crashes
  • Handle errors gracefully to improve user experience

With robust error handling, you can isolate bugs quicker and build more resilient apps.

Optimizing Page Speed

Next let's explore some common techniques for optimizing page speed using Safari developer tools.

Image Optimization

Safari provides multiple ways to optimize images:

  • Audit image sizes and formats using the Resources panel
  • Compress and resize images as needed
  • Lazy load offscreen images to improve TTI
  • Serve next-gen formats like WebP to Safari users
  • Remove unnecessary decorative images

With Safari's insight into image resources, you can significantly cut page weight and load times.

Script Loading

Optimizing script loading is key for performance:

  • Minimize parser-blocking JavaScript
  • Load non-critical scripts asynchronously
  • Dynamically create and load scripts
  • Code split bundles into logical chunks
  • Tree shake and minify code to reduce payload

Safari shows you exactly how scripts impact loading behavior so you can optimize delivery.

Caching Assets

Effective caching can boost repeat visit performance:

  • Set optimal cache lifetimes for static assets
  • Cache assets locally using service workers
  • Version assets linked to app release cycles
  • Avoid cache-busting query strings
  • Maximize cache reuse for returning users

The Resources panel helps you dial in caching for faster loads without staleness.

Layout Thrashing

Diagnosing layout thrashing is key for smooth UX:

  • Identify forced synchronous layouts
  • Defer non-critical DOM updates with requestAnimationFrame()
  • Avoid reading styles after writes during rendering
  • Batch DOM reads/writes together
  • Profile with Debugger to pinpoint problems

With Safari's performance tools, you can isolate and fix sources of jank and lag.

Wrap Up and Key Takeaways

Safari developer tools provide everything needed to build high-quality websites targeting Apple's ecosystem.

Key highlights include:

  • Debugging directly on iOS devices with Web Inspector
  • Stepping through JavaScript with advanced Debugger features
  • Auditing pages for standards compliance
  • Simulating mobile devices and networks during development
  • Optimizing performance using Network Throttling
  • Trying out experimental capabilities early
  • Discovering new Safari dev tools on platforms like DevHunt

Learning Safari developer tools allows you to find and fix cross-browser issues faster. You can optimize sites specifically for Safari and deliver stellar experiences to millions of Apple users worldwide.

With a comprehensive understanding of Safari's robust toolset, you can confidently build, debug and enhance modern progressive web apps. Safari developer tools help web developers succeed across platforms.

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