devtools-docs/index.html

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<h1>Overview</h1>

<p>The Chrome Developer Tools (DevTools for short), are a set web authoring and debugging tools
built into Google Chrome. The DevTools provide web developers deep access into the
internals of the browser and their web application. This overview of the DevTools 
points out the most popular and useful
features. If you haven't used the DevTools before, start here.
Even if you're an experienced web developer, you might pick up some tips.</p>

<p class="note"><strong>Note:</strong> If you are a web developer and want to get the latest version of
DevTools, you should use <a href="https://tools.google.com/dlpage/chromesxs">Google Chrome Canary</a>.</p>

<h2 id ="access">How to access the DevTools</h2>

<p>To access the DevTools, open a web page or web app in Google Chrome. Then take
one of the following actions:</p>

<ul>
<li>Select the <strong>Chrome menu</strong> <img src="images/chrome-menu.png"/> at the top-right of your browser window, then select
<strong>Tools</strong> > <strong>Developer tools</strong>.</li>
<li>Right-click on any page element and select <strong>Inspect element</strong>.</li>
</ul>


<p>There are several useful shortcuts for opening the DevTools:</p>

<ul>
<li>Use <span class="kbd">Ctrl</span>+<span class="kbd">Shift</span>+<span class="kbd">I</span> (or <span class="kbd">Cmd</span>+<span class="kbd">Opt</span>+<span class="kbd">I</span> on Mac) to open the DevTools.</li>
<li>Use <span class="kbd">Ctrl</span>+<span class="kbd">Shift</span>+<span class="kbd">J</span> (or <span class="kbd">Cmd</span>+<span class="kbd">Opt</span>+<span class="kbd">J</span> on Mac) to open the DevTools and bring
focus to the Console.</li>
<li>Use <span class="kbd">Ctrl</span>+<span class="kbd">Shift</span>+<span class="kbd">C</span> (or <span class="kbd">Cmd</span>+<span class="kbd">Shift</span>+<span class="kbd">C</span> on Mac) to open the DevTools in Inspect Element mode, or toggle Inspect Element mode if the DevTools are already open.</li>
</ul>


<p>For your day-to-day workflow, <a href="docs/shortcuts">learning the
shortcuts</a> will save you time.</p>

<h2 id="devtools-window">The DevTools window</h2>

<p>The DevTools are organised into task-oriented groups in the toolbar at the top
of the window. Each toolbar item and corresponding panel let you work with a
specific type of page or app information, including DOM elements, resources, and
sources.</p>

<p><img  class="screenshot" src="images/devtools-window.png"/></p>

<p>Overall, there are eight main groups of tools available view Developer Tools:
Elements, Resources, Network, Sources, Timeline, Profiles, Storage, Audits, and
Console. You can use the <span class="kbd">Ctrl</span>+<span class="kbd">[</span> and <span class="kbd">Ctrl</span>+<span class="kbd">]</span> shortcuts to move
between panels.</p>

<h2 id="dom-and-styles">Inspecting the DOM and styles</h2>

<p>The <strong><a href="docs/dom-and-styles.html">Elements</a></strong> panel lets you see
everything in one DOM tree, and allows inspection and on-the-fly editing of DOM
elements. You will often visit the Elements tabs when you need to identify the
HTML snippet for some aspect of the page. For example, you may be curious if an
image has an HTML id attribute, and what that attribute's value is.</p>
<a href="docs/dom-and-styles.html">
<p><img  class="screenshot" src="images/elements-panel.png"/></p>
</a>
<p><a href="docs/dom-and-styles.html">Read more about inspecting the DOM and styles</a></p>

<h2 id="console">Working with the console</h2>

<p>The JavaScript <a href="docs/console.md">Console</a> provides two
primary functions for developers testing web pages and applications:</p>

<ul>
<li>A place to log diagnostic information using methods provided by the <a href="docs/console-api.md">Console
API</a>, such as
<a href="docs/console-api.md#consolelogobject_object">console.log()</a>,
or <a href="docs/console-api.md#consoleprofilelabel">console.profile()</a>.</li>
<li>A shell prompt where you can enter commands and interact with the document and
the Chrome DevTools. You can evaluate expressions directly in the Console, and
can also use the methods provided by the <a href="docs/commandline-api.md">Command Line
API</a>, such as
<a href="docs/commandline-api.md#selector">$()</a> command for
selecting elements, or
<a href="docs/commandline-api.md#profile">profile()</a> to start the
CPU profiler.</li>
</ul>

<a href="docs/console.md">
<p><img  class="screenshot" src="docs/console-files/evaluate-expressions.png"/></p>
</a>


<p><a href="docs/console.md">Read more about working with the console</a></p>

<h2 id="debugging-javascript">Debugging JavaScript</h2>

<p>As the <strong>complexity</strong> of JavaScript applications increase, developers need
powerful debugging tools to help quickly discover the cause of an issue and fix
it efficiently. The Chrome DevTools include a number of useful tools to help
make <strong>debugging </strong>JavaScript less painful.</p>

<a href="docs/javascript-debugging.html">
<p><img  class="screenshot" src="images/javascript-debugging.png"/></p>
</a>

<p><a href="docs/javascript-debugging.html">Read more about how to debug JavaScript with the DevTools</a></p>

<h2 id="improving-network-performance">Improving network performance</h2>

<p>The <strong>Network</strong> panel provides insights into resources that are requested and
downloaded over the network in real time. Identifying and addressing those requests taking longer than expected is an essential step in optimizing your page.</p>

<a href="docs/network.md">
<p><img  class="screenshot" src="images/network-panel.png"/></p>
</a>

<p><a href="docs/network.md">Read more about how to improve your network performance</a></p>

<h2 id="audits">Audits</h2>

<p>The Audit panel can analyze a page as it loads and provide suggestions and
optimizations for decreasing page load time and increase perceived (and real)
responsiveness. For further insight, we recommend also installing the <a href="https://developers.google.com/speed/pagespeed/">PageSpeed</a> extension.</p>

<h2 id="timeline">Improving rendering performance</h2>

<p>The <strong>Timeline</strong> panel gives you a complete overview of where time is spent when
loading and using your web app or page. All events, from loading resources to
parsing JavaScript, calculating styles, and repainting are plotted on a
timeline.</p>

<a href="docs/timeline.md">
<p><img  class="screenshot" src="images/timeline-panel.png"/></p>
</a>

<p><a href="docs/timeline.md">Read more about how to improve rendering performance</a></p>

<h2 id="javascript-performance">JavaScript &amp; CSS performance</h2>

<p>The <strong>Profiles</strong> panel lets you profile the execution time and memory usage of a
web app or page. The <strong>Profiles</strong> panel includes a few profilers: a <strong>CPU
profiler, </strong>a <strong>JavaScript profiler</strong> and a <strong>Heap profiler</strong>. These help you to
understand where resources are being spent, and so help you to optimize your
code:</p>

<ul>
<li>The <strong>CPU profiler</strong> shows where execution time is spent in your page's
JavaScript functions.</li>
<li>The <strong>Heap profiler</strong> shows memory distribution by your page's JavaScript
objects and related DOM nodes.</li>
<li>The <strong>JavaScript </strong>profile shows where execution time is spent in your scripts</li>
</ul>

<a href="docs/profiles.html">
<p><img class="screenshot" src="images/profiles-panel.png"/></p>
</a>

<p><a href="docs/profiles.html">Read more about using how to improve JavaScript and CSS performance</a></p>

<h2 id="inspecting storage">Inspecting storage</h2>

<p>The <strong>Resources</strong> panel lets you inspect resources that are loaded in the
inspected page. It lets you interact with HTML 5 Database, Local Storage,
Cookies, AppCache, etc.</p>

<a href="docs/resource-panel.md">
<p><img  class="screenshot" src="images/resources-panel.png"/></p>
</a>

<p><a href="docs/resource-panel.md">Read more about inspecting storage resources</a></p>


<h2 id="further-reading">Further reading</h2>

<p>There are several other areas of the DevTools documentation that you might find of benefit to review.
These include:</p>

<ul>
<li><a href="docs/heap-profiling.html">Heap Profiling</a></li>
<li><a href="docs/cpu-profiling.html">CPU Profiling</a></li>
<li><a href="docs/mobile-emulation.html">Mobile Emulation</a></li>
<li><a href="docs/remote-debugging.html">Remote Debugging</a></li>
<li><a href="docs/videos.html">DevTools Videos</a></li>
</ul>

<h2 id="further-resources"">Further resources</h2>


<h3 id="get-more">Get more</h3>

<p>To more tips on the DevTools watch our regular show <a href="http://www.youtube.com/watch?v=ktwJ-EDiZoU&amp;list=PLNYkxOF6rcIBQ8j3J_PyM8JLAGKqZRByw">The
Breakpoint</a>
on YouTube.</p>

<p><a href="http://www.youtube.com/watch?v=ktwJ-EDiZoU&amp;list=PLNYkxOF6rcIBQ8j3J_PyM8JLAGKqZRByw"><img class="screenshot" src="images/image08.png" width="370px"/></a></p>

<p>You can also follow us on <a href="http://twitter.com/ChromiumDev">@ChromiumDev</a> or ask a question using the <a href="https://groups.google.com/forum/?fromgroups#!forum/google-chrome-developer-tools">forums</a>.</p>

<p><a href="http://twitter.com/ChromiumDev"><img class="screenshot" src="images/image13.png" width="370px"/></a></p>

<p>or checkout the Google Chrome Developers
<a href="https://plus.google.com/+GoogleChromeDevelopers/posts">G+</a> page.</p>

<p><a href="https://plus.google.com/+GoogleChromeDevelopers/posts"><img  class="screenshot" src="images/image00.png" width="370px"/></a></p>

<h3 id="take-the-course">Take the course</h3>
<p>Explore and master the DevTools with our free "Discover DevTools" coursen on <a href="http://discover-devtools.codeschool.com/">Code School</a>. </p>

<p><a href="http://discover-devtools.codeschool.com/"><img src="images/image15.png" width="370px"/></a></p>

<h3 id="get-involved">Get involved</h3>

<p>To submit a bug or a feature request on DevTools, please use issue tracker at
<a href="http://crbug.com/">http://crbug.com</a>. Please also mention "DevTools" in the bug
summary.</p>

<p><a href="http://crbug.com/"><img  class="screenshot" src="images/image02.png" width="200px"/></a></p>

<p>Anyone can also help make the DevTools better be directly
<a href="docs/contributing">contributing</a> back to the source.</p>


<h3 id="debugging-extensions">Debugging extensions</h3>

<p>Looking to use the DevTools to debug Chrome extensions? Watch <a href="http://www.youtube.com/watch?v=IP0nMv_NI1s">Developing and
Debugging extensions</a> or read the
<a href="https://developer.chrome.com/extensions/tut_debugging.html">Debugging</a>
tutorial.</p>


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