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<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>Extensions: Getting Started</title>
<link href="css/ApiRefStyles.css" rel="stylesheet" type="text/css">
</head>
<body>
<div id="container">
<a name="top"> </a>
<!-- API HEADER -->
<div id="pageHeader">
<!-- BREADCRUMB -->
<!-- TODO: Fix these hrefs -->
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<a href="./index.html">Google Chrome Extensions</a> >
<a href="devguide.html">Developer's Guide</a> >
Get Started (Hello, World!)
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<div id="pageTitle">
<h1>Get Started (Hello, World!)
</div>
</div> <!-- /pageHeader -->
<div id="pageContent">
<!-- SIDENAV -->
<div id="leftNav">
<ul>
<li> Overview </li>
<li> Get Started </li>
<li> Developer's Guide </li>
<li> Reference
<ul>
<li> chrome.* APIs
</li>
</ul>
</li>
</ul>
</div>
<div id="mainColumn">
<!-- TABLE OF CONTENTS -->
<div id="toc">
<p>Contents</p>
<ol>
<li> <a href="#browser">Get your browser ready</a> </li>
<li> <a href="#load">Create and load an extension</a> </li>
<li> <a href="#code">Add code to the extension</a> </li>
<li> <a href="#debug">Debug the extension</a> </li>
<li> <a href="#summary">Summary</a> </li>
</ol>
</div>
<!-- /TABLE OF CONTENTS -->
<!-- CONTENT -->
<p>
This tutorial walks you through creating a simple extension.
To complete this tutorial, you must have Windows;
Linux and Mac don't yet support extensions.
</p>
<h2 id="browser">Get your browser ready</h2>
<p>
To develop extensions for Google Chrome, you need to set up your browser:
</p>
<ol>
<li><a href="http://dev.chromium.org/getting-involved/dev-channel">Subscribe
to the Dev channel</a> of Google Chrome for Windows. </li>
<li><a href="http://dev.chromium.org/developers/creating-and-using-profiles">Create
a separate profile</a> for testing
<em>(optional but highly recommended)</em>.
Having a testing profile means that you can use Google Chrome
(with your default profile)
for everyday browsing,
even if your extension has horrible bugs.</li>
</ol>
<h2 id="load">Create and load an extension</h2>
<p>
In this section, you'll write a <em>toolstrip</em> —
an extension
that puts a bit of UI into the <em>toolbar</em>
at the bottom of the Google Chrome window.
</p>
<ol>
<li>
Create a folder somewhere on your computer to contain your extension's code.
We'll assume the folder is located at
<strong><code>c:\myext</code></strong>,
but it can be anywhere.
</li>
<li>
Inside your extension's folder,
create a text file called <strong><code>manifest.json</code></strong>,
and put this in it:
<pre>{
"name": "My First Extension",
"version": "1.0",
"description": "The first extension that I made.",
"toolstrips": [
"my_toolstrip.html"
]
}</pre>
</li>
<li>
In the same folder, create a text file called
<strong><code>my_toolstrip.html</code></strong>,
and put this in it:
<pre><div class="toolstrip-button">
<span>Hello, World!</span>
</div></pre>
</li>
<li> Load the extension:
<ol type="a">
<li>
Change the shortcut that you use to start the browser
(or create a new one)
so that it has the <code>--enable-extensions</code>
and <code>--load-extension</code> flags.
For example, if your extension is at <code>c:\myext</code>,
your shortcut might look something like this:
<pre>chrome.exe <span class="newCode">--enable-extensions --load-extension="c:\myext"</span></pre>
</li>
<li>Exit Google Chrome.
If you have a separate profile for testing,
you only need to exit the browser instances that use the testing profile. </li>
<li>Double-click the shortcut to start the browser.</li>
</ol>
<p>
<b>Note:</b>
For details on changing shortcut properties, see
<a href="http://dev.chromium.org/developers/creating-and-using-profiles">Creating
and Using Profiles</a>.</p>
</li>
</ol>
<p>
You should see the UI for your extension at the bottom left of the browser, looking something like this:
</p>
<table>
<tbody>
<tr>
<td align="center" width="33%"><img src="images/hw-1.gif"
alt="" /></td>
<td align="center" width="33%"><img src="images/hw-2.gif"
alt="" /></td>
<td align="center" width="33%"><img src="images/hw-3.gif"
alt="" /></td>
</tr>
<tr>
<th align="center" width="33%"> default appearance</th>
<th align="center" width="33%"> initial onhover appearance</th>
<th align="center" width="33%"> final onhover appearance</th>
</tr>
</tbody>
</table>
<p>
Your extension's button is automatically styled
to look like it belongs in the browser.
If you put the cursor over the button,
the button gets a nice, rounded edge,
just like the buttons in the bookmark bar.
After a while, a tooltip comes up, identifying the extension.
</p>
<p> [PENDING: troubleshooting info should go here.
what are symptoms of common typos, including misnamed files?
what are the symptoms if you don't have the dev channel?] </p>
<h2 id="code">Add code to the extension</h2>
<p> In this step, you'll make your extension <em>do</em> something besides just look good. </p>
<ol>
<li>
<p> Inside your extension's folder,
create a text file called <strong><code>hello_world.html</code></strong>,
and add the following code to it:</p>
<blockquote> <a href="samples/hello_world.txt">CSS
and JavaScript code for hello_world</a></blockquote>
</li>
<li>
<p> Edit <code>my_toolstrip.html</code>, so that it has the following code: </p>
<pre><div class="toolstrip-button"<span class="newCode"> onclick="window.open('hello_world.html')"</span>>
<span>Hello, World!</span>
</div></pre>
</li>
<li>
Restart the browser to load the new version of the extension.</li>
<li>Click the button.
A window should come up that displays <code>hello_world.html</code>. </li>
</ol>
<p> It should look something like this:</p>
<img src="images/hello_world-page.gif" alt="a window with a grid of images related to HELLO WORLD" />
<p> If you don't see that page,
try the instructions again,
following them exactly.
Don't try loading an HTML file that isn't in the extension's folder —
it won't work! </p>
<h2 id="debug">Debug the extension</h2>
<p>
You can use the browser's built-in developer tools
to view your extension's code,
display debugging output,
and debug your extension.
</p>
<ol>
<li>
<p> Edit <code>my_toolstrip.html</code>, so that it has the following code: </p>
<pre><span class="newCode"><script>
function helloWorld() {
var hwFile = 'hello_world.html';
console.log("in helloWorld()");
window.open(hwFile);
}
</script></span>
<div class="toolstrip-button" onclick="<span class="newCode">helloWorld();</span>">
<span>Hello, World!</span>
</div></pre>
<p> The relocated code still has the same effect,
but now it has some debugging output,
thanks to the call to <code>console.log()</code>.</p>
</li>
<li>
Restart the browser, so that it loads your new version of the extension.
<!--
This might be confusing.
Maybe we should instead cover location.reload() later,
after we've shown the console.
<div class="note">
<b>Tip:</b>
If you don't want to restart your browser,
you can get an updated version of the extension
by opening a new window.
The new window will contain the updated extension;
old windows will contain the old version.
</div>
-->
</li>
<li>
Right-click the <strong>Hello, World!</strong> button
(at the bottom left)
to bring up the Developer Tools window
for this instance of your toolstrip.
The window should look something like this:
<p>
<img src="images/devtools-1.gif" alt="" /> </p>
<!--
Possibly we should recommend starting the Dev Tools
using chrome://extensions, rather than right-click.
However, that adds some stuff (such as id)
that might be confusing.
-->
</li>
<li>
Click the <strong>Scripts</strong> button.
If necessary, choose <strong>my_toolstrip.html</strong>
from the list of scripts.
The result should be something like this:
<p>
<img src="images/devtools-2.gif" alt="" /> </p>
</li>
<li>
Set a debugging breakpoint at the <code>window.open()</code> statement
by clicking <strong>5</strong> in the left column:
<p>
<img src="images/devtools-3.gif" alt="" /> </p>
</li>
<li>
Click the Console button
(second from left, at the bottom of the Developer Tools window)
so that you can see both the code and the console.
<p>
<img src="images/devtools-4.gif" alt="" /></p>
</li>
<li>
Back in the main browser window,
click the <strong>Hello, World!</strong> button,
so that the extension begins executing.
You should see the output of <code>console.log()</code>
along with the line number,
and execution should stop just before
the call to <code>window.open()</code>.
<p>
<img src="images/devtools-5.gif" alt="" />
</p>
<p>
The Call Stack area at the right of the tools window shows that
the <code>helloWorld()</code> method was called by an anonymous function
that was called by <code>onclick</code>.
Anywhere in the Call Stack or console that you see a file and line number
(for example, "my_toolstrip.html:4"),
you can click that text to see the relevant line of code. </p>
</li>
<li>
In the upper right part of the tools window,
scroll down (if necessary) until you can see the local scope variables.
This section shows the current values of all variables in the current scope.
For example, you can see that <code>hwFile</code> is a local variable
that has the value "hello_world.html".
<p>
<img src="images/devtools-6.gif" alt="" /> </p>
</li>
<li>
Click the buttons at the upper right of the window
to resume execution or to step through the code.
Once the call to <code>window.open()</code> returns,
the main browser window should open a new tab
that displays the contents of <code>hello_world.html</code>.</li>
</ol>
<p>
You now know how to load and debug an extension!</p>
<h2 id="summary">Summary</h2>
<p>
[PENDING: Summarize what we did,
what it means,
what else we would've done if this were a real extension (e.g. package it),
and where to find more information.
Suggest where to go next.]</p>
</div> <!-- /mainColumn -->
</div> <!-- /pageContent -->
<div id="pageFooter" -->
Copyright 2009
<br />
TBD: copyright/license should be automatically included here
</div> <!-- /pageFooter -->
</div> <!-- /container -->
</body>
</html>
|
