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1 siliconforks 197 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
2 siliconforks 2 <html>
3     <head>
4     <title>JSCoverage user manual</title>
5 siliconforks 198 <link rel="stylesheet" type="text/css" href="sh_nedit.min.css">
6     <link rel="stylesheet" type="text/css" href="doc.css">
7 siliconforks 328 <script type="text/javascript" src="sh_main.min.js"></script>
8     <script type="text/javascript" src="sh_html.min.js"></script>
9     <script type="text/javascript" src="sh_javascript.min.js"></script>
10 siliconforks 2 </head>
11 siliconforks 198 <body onload="sh_highlightDocument();">
12 siliconforks 2
13     <h1>JSCoverage user manual</h1>
14    
15     <p>
16 siliconforks 328 JSCoverage is a tool that measures code coverage for JavaScript programs.
17 siliconforks 2 </p>
18    
19     <p>
20 siliconforks 115 JSCoverage works by adding instrumentation to JavaScript code before it is
21     executed in a web browser. JSCoverage provides several alternative ways of doing
22     this:
23 siliconforks 2 </p>
24    
25 siliconforks 115 <ul>
26     <li>The simplest method is to use the <code>jscoverage</code> program to generate
27     instrumented JavaScript files.
28     </li>
29     <li>Alternatively, you can use the <code>jscoverage-server</code> program, a simple web server that instruments
30     JavaScript code as it is served.
31     </li>
32     <li>Finally, <code>jscoverage-server</code> can be run with the <code>--proxy</code> option to
33     act as a proxy server which instruments any JavaScript code proxied through it.
34     </li>
35     </ul>
36 siliconforks 2
37 siliconforks 115 <p>
38     The <code>jscoverage-server</code> program (with or without the <code>--proxy</code>
39     option) has the advantage of being able to store coverage reports to the filesystem.
40     </p>
41    
42 siliconforks 225 <h2>Compiling JSCoverage</h2>
43 siliconforks 2
44     <p>
45     You can compile JSCoverage on GNU/Linux or Microsoft Windows, using GCC. On
46     Windows you will require <a href="http://cygwin.com/">Cygwin</a> or <a
47     href="http://mingw.org/">MinGW/MSYS</a>.
48     </p>
49    
50     <p>
51     You can extract and compile the code with the following commands:
52     </p>
53    
54     <pre>
55 siliconforks 115 tar jxvf jscoverage-0.4.tar.bz2
56     cd jscoverage-0.4/
57 siliconforks 2 ./configure
58     make
59     </pre>
60    
61     <p>
62 siliconforks 115 This will create the <code>jscoverage</code> and <code>jscoverage-server</code>
63     executables (<code>jscoverage.exe</code> and <code>jscoverage-server.exe</code>
64     on Windows). You can install the executables in <code>/usr/local</code> with the
65     command:
66 siliconforks 2 </p>
67    
68     <pre>
69     make install
70     </pre>
71    
72     <p>
73 siliconforks 115 Alternatively, you may simply copy the <code>jscoverage</code> executable and/or
74     the <code>jscoverage-server</code> executable to a suitable location in your
75     <code>PATH</code>.
76 siliconforks 2 </p>
77    
78 siliconforks 115 <h2>Using the <code>jscoverage</code> program</h2>
79 siliconforks 2
80     <p>
81 siliconforks 328 To demonstrate how the <code>jscoverage</code> program works, we will use the
82     trivial example JavaScript code located in the
83     <code>doc/example/</code> directory of the JSCoverage distribution. You can run
84     this example by viewing the file <code>doc/example/index.html</code> in your web browser.
85 siliconforks 2 </p>
86    
87 siliconforks 328 <p>
88     Generating code coverage statistics for this example using the
89     <code>jscoverage</code> program involves the following steps:
90     </p>
91    
92 siliconforks 2 <h3>1. Instrumenting code</h3>
93    
94     <p>
95 siliconforks 115 The first step is to add instrumentation to your JavaScript code. You do this by
96     executing <code>jscoverage</code> with two arguments:
97 siliconforks 2 </p>
98    
99     <pre>
100     jscoverage <var>SOURCE-DIRECTORY</var> <var>DESTINATION-DIRECTORY</var>
101     </pre>
102    
103     <p>
104     <var>SOURCE-DIRECTORY</var> is the directory containing the JavaScript code to be instrumented,
105     and <var>DESTINATION-DIRECTORY</var> is the name of the
106     directory to which <code>jscoverage</code> should output the instrumented code.
107     The <code>jscoverage</code> program will create <var>DESTINATION-DIRECTORY</var> if necessary and (recursively) copy
108     <var>SOURCE-DIRECTORY</var> to <var>DESTINATION-DIRECTORY</var>, instrumenting
109     any files ending with a <code>.js</code> extension.
110     </p>
111    
112     <p>
113 siliconforks 328 The directory structure under <var>SOURCE-DIRECTORY</var> is preserved, so that if you have a file
114 siliconforks 2 <code><var>SOURCE-DIRECTORY</var>/dir/index.html</code> referencing the script
115     <code><var>SOURCE-DIRECTORY</var>/dir/script.js</code>, then
116     <code>jscoverage</code> will create a copy of the HTML file at
117     <code><var>DESTINATION-DIRECTORY</var>/dir/index.html</code> and an instrumented
118     version of the script at
119     <code><var>DESTINATION-DIRECTORY</var>/dir/script.js</code>.
120     </p>
121    
122     <table>
123     <tr>
124     <td><pre>
125     <var>SOURCE-DIRECTORY</var>/
126     dir/
127     index.html
128     script.js
129    
130     </pre></td>
131     <td class="arrow">&rarr;</td>
132     <td><pre>
133     <var>DESTINATION-DIRECTORY</var>/
134     dir/
135     index.html
136     script.js [instrumented]
137     jscoverage.html
138     </pre></td>
139     </tr>
140     </table>
141    
142     <p>
143     In addition, <code>jscoverage</code> creates a file called <code>jscoverage.html</code>
144     which is used to execute the instrumented code.
145     </p>
146    
147 siliconforks 328 <p>
148     To instrument the code in the <code>doc/example/</code> directory, execute the
149     following command from the top-level directory of the JSCoverage distribution:
150     </p>
151    
152     <pre>
153     jscoverage doc/example doc/instrumented
154     </pre>
155    
156     <p>
157     This will create the directory <code>doc/instrumented/</code> and place an
158     instrumented copy of the code from <code>doc/example/</code> in
159     <code>doc/instrumented/</code>.
160     </p>
161    
162     <table>
163     <tr>
164     <td><pre>
165     doc/example/
166     index.html
167     script.js
168    
169     </pre></td>
170     <td class="arrow">&rarr;</td>
171     <td><pre>
172     doc/instrumented/
173     index.html
174     script.js [instrumented]
175     jscoverage.html
176     </pre></td>
177     </tr>
178     </table>
179    
180 siliconforks 115 <h3>2. Executing the instrumented code in a web browser</h3>
181 siliconforks 2
182     <p>
183 siliconforks 328 Open the generated <code>jscoverage.html</code> file
184     (<code>doc/instrumented/jscoverage.html</code>) in your web browser.
185 siliconforks 2 The page contains a tabbed user interface:
186     </p>
187    
188     <ul>
189     <li>The "Browser" tab is used to display pages with instrumented scripts.
190     <li>The "Summary" tab is used to display code coverage data.
191     <li>The "Source" tab is used to display JavaScript code, showing the number of times
192     each line of code was executed.
193     <li>The "About" tab displays information about the current version of JSCoverage.
194     </ul>
195    
196 siliconforks 197 <p><img src="screenshot.png" alt="Screenshot"></p>
197 siliconforks 2
198     <p>
199     The "Browser" tab contains an <code>&lt;iframe&gt;</code>, which is initially empty.
200     You can load a page into this frame by
201 siliconforks 328 entering its URL into the "URL" input field.
202 siliconforks 64 You can load any page located in <code><var>DESTINATION-DIRECTORY</var>/</code>
203     or a subdirectory underneath <code><var>DESTINATION-DIRECTORY</var>/</code>; loading a page
204     from outside <code><var>DESTINATION-DIRECTORY</var>/</code>, or from a foreign web
205     server, will give unexpected results.
206 siliconforks 2 </p>
207    
208     <p>
209 siliconforks 328 For example, you can load the file <code>doc/instrumented/index.html</code> by typing
210     <code>index.html</code> in the "URL" input field (relative URLs are acceptable).
211 siliconforks 2 </p>
212    
213     <p>
214 siliconforks 328 Alternatively, you can load a page into the <code>&lt;iframe&gt;</code> by
215     appending the page URL to the query string of the <code>jscoverage.html</code> URL.
216     For example, appending <code>?index.html</code> to the <code>jscoverage.html</code> URL
217     will cause the <code>index.html</code> file to be loaded automatically.
218 siliconforks 2 </p>
219    
220 siliconforks 197 <p><img src="screenshot2.png" alt="Screenshot"></p>
221 siliconforks 2
222     <p>
223 siliconforks 328 For this example, the JavaScript does not execute automatically:
224 siliconforks 2 you have to select one of the radio buttons to execute the code.
225     </p>
226    
227 siliconforks 197 <p><img src="screenshot3.png" alt="Screenshot"></p>
228 siliconforks 2
229 siliconforks 115 <h3>3. Generating a coverage report</h3>
230 siliconforks 2
231     <p>
232 siliconforks 328 Once the JavaScript code in the page in the "Browser" tab has been executed, click on
233     the "Summary" tab. This will display the current code coverage statistics.
234 siliconforks 2 </p>
235    
236 siliconforks 197 <p><img src="screenshot4.png" alt="Screenshot"></p>
237 siliconforks 2
238     <p>
239 siliconforks 41 You can click the checkbox to show a list of statements missed during execution.
240 siliconforks 2 </p>
241    
242 siliconforks 197 <p><img src="screenshot5.png" alt="Screenshot"></p>
243 siliconforks 2
244 siliconforks 41 <p>
245     You can click one of the links to get a detailed view of a JavaScript source file.
246     </p>
247    
248 siliconforks 197 <p><img src="screenshot6.png" alt="Screenshot"></p>
249 siliconforks 41
250 siliconforks 328 <p>
251     As long as you do not reload the
252     <code>jscoverage.html</code> page, the coverage report statistics are
253     cumulative. If you execute more JavaScript in the frame in the "Browser" tab (e.g., by clicking on a link to
254     another scripted page, or by reloading the frame containing a scripted
255     page) and switch to the "Summary" tab again,
256     the coverage report will combine the statistics from the previous report with any newly generated statistics.
257     Reloading <code>jscoverage.html</code> resets all code coverage statistics to zero.
258     </p>
259    
260 siliconforks 14 <h2>Inverted mode</h2>
261    
262     <p>
263 siliconforks 41 In some situations it may be difficult to execute your code within the
264 siliconforks 14 JSCoverage "Browser" tab. For example, the code may assume that it is running in
265     the top-level browser window, generating errors if it is executed from within a
266     frame. JSCoverage has an alternative mode of operation, called <dfn>inverted
267 siliconforks 41 mode</dfn>, which may be useful in this case.
268 siliconforks 14 </p>
269    
270     <p>
271     Normally you load <code>jscoverage.html</code> in your web browser, and in its
272     "Browser" tab you launch your test code. In inverted mode, you do the
273     opposite: you load your test page directly in your web browser, and from there
274     you launch JSCoverage. To do this you need to add some code to your test page:
275     </p>
276    
277 siliconforks 198 <pre class="sh_javascript">
278     window.open('path/to/jscoverage.html');
279 siliconforks 14 </pre>
280    
281     <p>
282     The <code>"path/to/jscoverage.html"</code> should be a URL pointing to the
283     location of the <code>jscoverage.html</code> file (remember, this will be in the
284     top level of the <var>DESTINATION-DIRECTORY</var> you specified when running
285     the <code>jscoverage</code> executable).
286     </p>
287    
288     <p>
289     You can place this code wherever you like in your page: for example, you could
290     attach it to a button:
291     </p>
292    
293 siliconforks 198 <pre class="sh_html">
294     &lt;button onclick="window.open('path/to/jscoverage.html');"&gt;Coverage report&lt;/button&gt;
295 siliconforks 14 </pre>
296    
297     <p>
298 siliconforks 37 Note that you <em>must</em> use a <code>window.open</code> call; simply making a
299     link to <code>jscoverage.html</code> is not sufficient.
300     </p>
301    
302     <p>
303 siliconforks 14 An example is located in the <code>doc/example-inverted</code> directory.
304 siliconforks 328 You can instrument the code with the <code>jscoverage</code> program:
305 siliconforks 14 </p>
306    
307     <pre>
308     jscoverage doc/example-inverted doc/instrumented-inverted
309     </pre>
310    
311     <p>
312 siliconforks 328 You can load the page <code>doc/instrumented-inverted/index.html</code>
313     directly in your web browser.
314 siliconforks 14 From this page, you select one of the radio buttons and then click the "Coverage
315     report" button to launch the JSCoverage report.
316     </p>
317    
318 siliconforks 273 <p>
319     Another example is located in the <code>doc/example-jsunit</code> directory.
320     See the <a href="faq.html#jsunit">FAQ</a> for more information.
321     </p>
322    
323 siliconforks 115 <h2><code>jscoverage</code> command line options</h2>
324 siliconforks 19
325     <p>
326     The <code>jscoverage</code> program accepts the following options:
327     </p>
328    
329     <dl>
330     <dt><code>-h</code>, <code>--help</code>
331     <dd>Display a brief help message.
332     <dt><code>-V</code>, <code>--version</code>
333     <dd>Display the version of the program.
334     <dt><code>-v</code>, <code>--verbose</code>
335     <dd>Explain what is being done.
336 siliconforks 207 <dt><code>--encoding=<var>ENCODING</var></code>
337     <dd>Assume that all JavaScript files use the given character encoding. The
338     default is ISO-8859-1.
339 siliconforks 19 <dt><code>--exclude=<var>PATH</var></code>
340     <dd>The command
341     <pre>
342     jscoverage --exclude=<var>PATH</var> <var>SOURCE-DIRECTORY</var> <var>DESTINATION-DIRECTORY</var>
343     </pre>
344     copies <var>SOURCE-DIRECTORY</var> to <var>DESTINATION-DIRECTORY</var>
345     recursively, but does not copy <var>SOURCE-DIRECTORY</var>/<var>PATH</var>.
346 siliconforks 41 <var>PATH</var> must be a complete path relative to <var>SOURCE-DIRECTORY</var>.
347 siliconforks 19 <var>PATH</var> can be a file or a directory (in which case the directory and
348     its entire contents are skipped). This option may be given multiple times.
349 siliconforks 207 <dt><code>--no-highlight</code>
350     <dd>Do not perform syntax highlighting of JavaScript code.
351 siliconforks 19 <dt><code>--no-instrument=<var>PATH</var></code>
352     <dd>The command
353     <pre>
354 siliconforks 41 jscoverage --no-instrument=<var>PATH</var> <var>SOURCE-DIRECTORY</var> <var>DESTINATION-DIRECTORY</var>
355 siliconforks 19 </pre>
356     copies <var>SOURCE-DIRECTORY</var> to <var>DESTINATION-DIRECTORY</var>
357     recursively, but does not instrument any JavaScript code in
358     <var>SOURCE-DIRECTORY</var>/<var>PATH</var>. <var>PATH</var> must be a complete
359 siliconforks 59 path relative to <var>SOURCE-DIRECTORY</var>. <var>PATH</var> can be a
360 siliconforks 19 (JavaScript) file or a directory (in which case any JavaScript files located
361     anywhere underneath the directory are not instrumented). This option may be
362     given multiple times.
363     </dl>
364    
365     <h2>Query string options</h2>
366    
367     <p>
368     When accessing <code>jscoverage.html</code> in a web browser, you may provide a
369     query string consisting of options separated by ampersand (<code>&amp;</code>)
370     or semicolon (<code>;</code>). Any option not containing an equals sign
371     (<code>=</code>) is considered to be a URL which will be loaded in the "Browser"
372     tab.
373     </p>
374    
375     <dl>
376     <dt><code>u=<var>URL</var></code>, <code>url=<var>URL</var></code>
377     <dd>Load <var>URL</var> in the "Browser" tab. (This is the same as specifying
378     an option without an equals sign.)
379     <dt><code>m=<var>BOOLEAN</var></code>, <code>missing=<var>BOOLEAN</var></code>
380     <dd>Determines whether to initially display the "Missing" column in the "Summary"
381     tab. <var>BOOLEAN</var> can be
382 siliconforks 59 <code>true</code>, <code>t</code>, <code>yes</code>, <code>y</code>, <code>on</code>, <code>1</code>
383 siliconforks 19 (to display the "Missing" column), or
384     <code>false</code>, <code>f</code>, <code>no</code>, <code>n</code>, <code>off</code>, <code>0</code>
385 siliconforks 41 (to hide the "Missing" column). By default, the "Missing" column is not displayed.
386 siliconforks 19 </dl>
387    
388 siliconforks 115 <h2>Using the <code>jscoverage-server</code> program</h2>
389    
390     <p>
391 siliconforks 198 The <code>jscoverage-server</code> program is a simple web server. You can use
392     <code>jscoverage-server</code> to serve files from the <code>doc/example/</code>
393     directory:
394 siliconforks 115 </p>
395    
396     <pre>
397     cd doc/example
398     jscoverage-server --verbose
399     </pre>
400    
401     <p>
402 siliconforks 198 Once the server is running, you can access the JSCoverage web interface by
403     visiting the URL <code>http://127.0.0.1:8080/jscoverage.html</code>, and you can
404     load the <code>doc/example/index.html</code> file by entering
405     <code>index.html</code> in the "URL" input field. (Or you can do this all in
406     one step by loading the URL
407     <code>http://127.0.0.1:8080/jscoverage.html?index.html</code> in your web
408     browser.) The
409     <code>jscoverage-server</code> program automatically instruments any served
410 siliconforks 115 JavaScript code, so that code coverage data will be gathered as the code is
411     executed in your browser.
412     </p>
413    
414     <p>
415     The web interface is slightly different from that generated by the
416     <code>jscoverage</code> program: it has a new tab named "Store".
417     To store coverage data, click the "Store" tab.
418     </p>
419    
420 siliconforks 197 <p><img src="screenshot7.png" alt="Screenshot"></p>
421 siliconforks 115
422     <p>
423 siliconforks 326 When you click the "Store Report" button, the coverage data will be saved to a directory named <code>jscoverage-report/</code>.
424 siliconforks 115 You can view this stored report at any time by opening the file <code>jscoverage-report/jscoverage.html</code> in
425 siliconforks 198 your web browser - you don't need the <code>jscoverage-server</code> running to access it.
426 siliconforks 115 </p>
427    
428     <p>
429     If you use the "Store" tab again to store coverage data, the new data will be merged with
430     the previous data in the <code>jscoverage-report/</code> directory. This can be useful,
431     for instance, if you wish to run a set of tests in different browsers and generate an
432     aggregate report which combines the data for all of them.
433     </p>
434    
435     <p>
436     You can stop the server by running another instance of <code>jscoverage-server</code> with the
437     <code>--shutdown</code> option:
438     </p>
439    
440     <pre>
441     jscoverage-server --shutdown
442     </pre>
443    
444     <h2>Using <code>jscoverage-server --proxy</code></h2>
445    
446     <p>
447     To use <code>jscoverage-server</code> as a proxy server, use the <code>--proxy</code> option:
448     </p>
449    
450     <pre>
451     jscoverage-server --verbose --proxy
452     </pre>
453    
454     <p>
455     Configure your browser to use an HTTP proxy with address 127.0.0.1 and port 8080.
456     You can then generate code coverage data for a web page on the server <code>example.com</code>
457     by accessing the JSCoverage web interface at the special URL <code>http://example.com/jscoverage.html</code>.
458     Note that this URL is not provided by the <code>example.com</code> server; it is automatically generated
459     by the proxy server whenever a URL with path <code>/jscoverage.html</code> is requested.
460     </p>
461    
462     <h2><code>jscoverage-server</code> command line options</h2>
463    
464     <dl>
465     <dt><code>-h</code>, <code>--help</code>
466     <dd>Display a brief help message.
467     <dt><code>-V</code>, <code>--version</code>
468     <dd>Display the version of the program.
469     <dt><code>-v</code>, <code>--verbose</code>
470     <dd>Explain what is being done.
471     <dt><code>--document-root=<var>PATH</var></code>
472     <dd>Serve web content from the directory given by <var>PATH</var>. The default is
473     the current directory. This option may not be given with the <code>--proxy</code> option.
474 siliconforks 207 <dt><code>--encoding=<var>ENCODING</var></code>
475     <dd>Assume that all JavaScript files use the given character encoding. The
476     default is ISO-8859-1. Note that if you use the <code>--proxy</code> option, the
477     character encoding will be determined from the <code>charset</code> parameter in
478     the <code>Content-Type</code> HTTP header.
479 siliconforks 115 <dt><code>--ip-address=<var>ADDRESS</var></code>
480     <dd>Run the server on the IP address given by <var>ADDRESS</var>. The default is <code>127.0.0.1</code>. Specify
481     <code>0.0.0.0</code> to use any address.
482 siliconforks 207 <dt><code>--no-highlight</code>
483     <dd>Do not perform syntax highlighting of JavaScript code.
484 siliconforks 115 <dt><code>--no-instrument=<var>URL</var></code>
485     <dd>Do not instrument JavaScript code from <var>URL</var>. If you are running <code>jscoverage-server</code>
486     with the <code>--proxy</code> option, <var>URL</var> should be a full URL. For example:
487     <pre>
488     jscoverage-server --proxy --no-instrument=http://example.com/scripts/
489     </pre>
490     Without <code>--proxy</code>, <var>URL</var> should be only the path portion of a URL:
491     <pre>
492     jscoverage-server --no-instrument=/scripts/
493     </pre>
494     This option may be given multiple times.
495     <dt><code>--port=<var>PORT</var></code>
496     <dd>Run the server on the port given by <var>PORT</var>. The default is port 8080.
497     <dt><code>--proxy</code>
498     <dd>Run as a proxy server.
499     <dt><code>--report-dir=<var>PATH</var></code>
500     <dd>Use the directory given by <var>PATH</var> for storing coverage reports. The default is
501     <code>jscoverage-report/</code> in the current directory.
502     <dt><code>--shutdown</code>
503     <dd>Stop a running instance of the server.
504     </dl>
505    
506 siliconforks 158 <h2>Advanced topics</h2>
507    
508 siliconforks 198 <h3>Storing coverage reports programmatically</h3>
509    
510     <p>
511     If you are executing a test suite using <code>jscoverage-server</code>, you can
512     store a coverage report programmatically by having your test suite call the
513     <code>jscoverage_report</code> function (automatically generated by
514     <code>jscoverage-server</code>) after all your tests have finished running:
515     </p>
516    
517     <pre class="sh_javascript">
518 siliconforks 270 if (window.jscoverage_report) {
519     jscoverage_report();
520 siliconforks 198 }
521     </pre>
522    
523     <p>
524     You can specify the name of the directory in which to store the report by
525     passing the name as a parameter to the <code>jscoverage_report</code> function:
526     </p>
527    
528     <pre class="sh_javascript">
529 siliconforks 270 if (window.jscoverage_report) {
530 siliconforks 198 // determine the directory name based on the browser
531     var directory;
532     if (/MSIE/.test(navigator.userAgent)) {
533     directory = 'IE';
534     }
535     else {
536     directory = 'other';
537     }
538 siliconforks 270 jscoverage_report(directory);
539 siliconforks 198 }
540     </pre>
541    
542     <p>
543     This directory will be a subdirectory under the <code>jscoverage-report/</code>
544     directory (or whatever is specified with the <code>--report-dir</code> option).
545     Using the above example, the report would be stored to either
546     <code>jscoverage-report/IE/</code> or <code>jscoverage-report/other/</code>.
547     </p>
548    
549 siliconforks 201 <p>
550     It is not necessary that your test suite be executed within the
551     <code>jscoverage.html</code> web interface to store a coverage report. The URL
552     of the test suite can simply be loaded directly in a web browser.
553     </p>
554    
555 siliconforks 273 <p>
556     The example in <code>doc/example-jsunit/</code> demonstrates storing coverage
557     reports programmatically.
558     </p>
559    
560 siliconforks 240 <h3>Ignoring certain lines of code</h3>
561 siliconforks 158
562     <p>
563     Sometimes you may wish to exclude certain lines of code from coverage
564     statistics. Some lines of code may be executed only in certain browsers; other
565 siliconforks 198 lines should never be executed at all (they may be present only to detect
566 siliconforks 240 programming errors). You can use specially formatted comments in your code to
567     tell JSCoverage to ignore certain lines of code. These lines will not be
568     included in the JSCoverage "Summary" tab; in the "Source" tab, these lines will
569     be indicated with the color yellow.
570 siliconforks 158 </p>
571    
572     <p>
573 siliconforks 240 These comments take the following form:
574 siliconforks 158 </p>
575    
576     <pre class="sh_javascript">
577     //#JSCOVERAGE_IF <var>CONDITION</var>
578     ...
579     //#JSCOVERAGE_ENDIF
580     </pre>
581    
582     <p>
583 siliconforks 240 The comment must be formatted exactly as shown: it must be a line comment
584     starting with <code>//</code>, it must start in the first column, and it must be
585     followed by <code>#JSCOVERAGE_IF</code> or <code>#JSCOVERAGE_ENDIF</code> in
586     uppercase letters with no intervening white space.
587     </p>
588    
589     <p>
590 siliconforks 158 The <var>CONDITION</var> is an ordinary JavaScript expression; if this
591     expression evaluates to <code>true</code>, then the lines of code between the
592 siliconforks 240 <code>//#JSCOVERAGE_IF</code> and <code>//#JSCOVERAGE_ENDIF</code> comments are
593 siliconforks 158 included in coverage statistics; otherwise, they are excluded from coverage
594     statistics.
595     </p>
596    
597     <p>
598 siliconforks 240 For example:
599 siliconforks 158 </p>
600    
601 siliconforks 240 <pre class="sh_javascript">
602     function log(s) {
603     if (window.console) {
604     //#JSCOVERAGE_IF window.console
605     console.log(s);
606     //#JSCOVERAGE_ENDIF
607     }
608     }
609     </pre>
610    
611 siliconforks 158 <p>
612 siliconforks 240 You can exclude code from coverage statistics unconditionally by using
613     <code>#JSCOVERAGE_IF 0</code> or <code>#JSCOVERAGE_IF false</code>:
614 siliconforks 158 </p>
615    
616     <pre class="sh_javascript">
617 siliconforks 240 function f(x) {
618     if (x === null) {
619     //#JSCOVERAGE_IF 0
620     throw 'error';
621 siliconforks 158 //#JSCOVERAGE_ENDIF
622     }
623 siliconforks 240 ...
624 siliconforks 158 </pre>
625    
626     <p>
627 siliconforks 240 There is also a short form, which must appear on the line preceding an
628     <code>if</code> statement:
629 siliconforks 158 </p>
630    
631     <pre class="sh_javascript">
632 siliconforks 240 //#JSCOVERAGE_IF
633     if (...) {
634     ...
635     }
636     else if (...) {
637     ...
638     }
639     ...
640     else {
641     ...
642     }
643 siliconforks 158 </pre>
644    
645     <p>
646 siliconforks 240
647     In this form, there is no condition on the <code>//#JSCOVERAGE_IF</code> line
648     and no <code>//#JSCOVERAGE_ENDIF</code>. You use this form to tell JSCoverage
649     that you expect only one branch of the <code>if</code> statement to be executed;
650     coverage statistics will not be collected for the other branch(es). For
651     example:
652 siliconforks 158 </p>
653    
654     <pre class="sh_javascript">
655 siliconforks 240 function log(s) {
656     //#JSCOVERAGE_IF
657     if (window.console) {
658     console.log(s);
659 siliconforks 158 }
660 siliconforks 240 else if (window.opera) {
661     opera.postError(s);
662     }
663     else {
664     throw 'no logging function available';
665     }
666 siliconforks 158 }
667     </pre>
668    
669 siliconforks 201 <p>
670 siliconforks 240 Currently, <code>//#JSCOVERAGE_IF</code> comments are not recorded in stored coverage reports.
671 siliconforks 201 </p>
672    
673 siliconforks 2 <h2>Caveats</h2>
674    
675     <ul>
676     <li>JSCoverage adds instrumentation to JavaScript code, which will slow down execution speed.
677     Expect instrumented code to take at least twice as much time to run.
678     <li>JSCoverage currently instruments only <code>.js</code> files; it does not instrument code in <code>&lt;script&gt;</code>
679     elements in HTML files.
680     <li>HTML files must use relative URLs to reference scripts. If you use an absolute URL, your page will reference
681     the original uninstrumented script rather than the instrumented one, and no code coverage data will be collected.
682     <li>JSCoverage instruments physical lines of code rather than logical JavaScript statements; it works bests with code
683     that has exactly one statement per line. If you put multiple statements on a line, or split a line across two or more
684     statements, you may get strange results.
685     <li>JSCoverage uses frames. Some web pages that use frames may not function properly when run under JSCoverage, especially
686     those which try to access the top-level frame (<code>window.top</code>, <code>target="_top"</code>, etc.).
687 siliconforks 198 <li>JSCoverage is distributed without any warranty. See the <a href="license.html">license</a> for more details.
688 siliconforks 2 </ul>
689    
690     <address>
691 siliconforks 147 Copyright &copy; 2007, 2008 <a href="http://siliconforks.com/"><img src="siliconforks-16x16.png" width="16" height="16" class="icon" alt="Silicon Forks"></a> <a href="http://siliconforks.com/">siliconforks.com</a><br>
692 siliconforks 2 <a href="mailto:jscoverage@siliconforks.com">jscoverage@siliconforks.com</a>
693     </address>
694    
695     </body>
696     </html>

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