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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     <script src="sh_main.min.js"></script>
7     <script src="sh_html.min.js"></script>
8     <script src="sh_javascript.min.js"></script>
9     <link rel="stylesheet" type="text/css" href="doc.css">
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 198 JSCoverage is a tool that measures code coverage in 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 198 Using the <code>jscoverage</code> program involves the following steps:
82 siliconforks 2 </p>
83    
84     <h3>1. Instrumenting code</h3>
85    
86     <p>
87 siliconforks 115 The first step is to add instrumentation to your JavaScript code. You do this by
88     executing <code>jscoverage</code> with two arguments:
89 siliconforks 2 </p>
90    
91     <pre>
92     jscoverage <var>SOURCE-DIRECTORY</var> <var>DESTINATION-DIRECTORY</var>
93     </pre>
94    
95     <p>
96     <var>SOURCE-DIRECTORY</var> is the directory containing the JavaScript code to be instrumented,
97     and <var>DESTINATION-DIRECTORY</var> is the name of the
98     directory to which <code>jscoverage</code> should output the instrumented code.
99     The <code>jscoverage</code> program will create <var>DESTINATION-DIRECTORY</var> if necessary and (recursively) copy
100     <var>SOURCE-DIRECTORY</var> to <var>DESTINATION-DIRECTORY</var>, instrumenting
101     any files ending with a <code>.js</code> extension.
102     </p>
103    
104     <p>
105     For example, if you have a file
106     <code><var>SOURCE-DIRECTORY</var>/dir/index.html</code> referencing the script
107     <code><var>SOURCE-DIRECTORY</var>/dir/script.js</code>, then
108     <code>jscoverage</code> will create a copy of the HTML file at
109     <code><var>DESTINATION-DIRECTORY</var>/dir/index.html</code> and an instrumented
110     version of the script at
111     <code><var>DESTINATION-DIRECTORY</var>/dir/script.js</code>.
112     </p>
113    
114     <table>
115     <tr>
116     <td><pre>
117     <var>SOURCE-DIRECTORY</var>/
118     dir/
119     index.html
120     script.js
121    
122     </pre></td>
123     <td class="arrow">&rarr;</td>
124     <td><pre>
125     <var>DESTINATION-DIRECTORY</var>/
126     dir/
127     index.html
128     script.js [instrumented]
129     jscoverage.html
130     </pre></td>
131     </tr>
132     </table>
133    
134     <p>
135     In addition, <code>jscoverage</code> creates a file called <code>jscoverage.html</code>
136     which is used to execute the instrumented code.
137     </p>
138    
139 siliconforks 115 <h3>2. Executing the instrumented code in a web browser</h3>
140 siliconforks 2
141     <p>
142     Open <code>jscoverage.html</code> in your web browser.
143     The page contains a tabbed user interface:
144     </p>
145    
146     <ul>
147     <li>The "Browser" tab is used to display pages with instrumented scripts.
148     <li>The "Summary" tab is used to display code coverage data.
149     <li>The "Source" tab is used to display JavaScript code, showing the number of times
150     each line of code was executed.
151     <li>The "About" tab displays information about the current version of JSCoverage.
152     </ul>
153    
154 siliconforks 197 <p><img src="screenshot.png" alt="Screenshot"></p>
155 siliconforks 2
156     <p>
157     The "Browser" tab contains an <code>&lt;iframe&gt;</code>, which is initially empty.
158     You can load a page into this frame by
159     entering its URL into the "URL" input field. For example, to load
160     the file <code><var>DESTINATION-DIRECTORY</var>/dir/index.html</code>, you can
161     enter the relative URL <code>dir/index.html</code> into the input field.
162 siliconforks 64 You can load any page located in <code><var>DESTINATION-DIRECTORY</var>/</code>
163     or a subdirectory underneath <code><var>DESTINATION-DIRECTORY</var>/</code>; loading a page
164     from outside <code><var>DESTINATION-DIRECTORY</var>/</code>, or from a foreign web
165     server, will give unexpected results.
166 siliconforks 2 </p>
167    
168 siliconforks 115 <h3>3. Generating a coverage report</h3>
169 siliconforks 2
170     <p>
171     Once the JavaScript code in the page in the "Browser" tab has been executed, click on
172     the "Summary" tab. This will display the current code coverage statistics.
173     </p>
174    
175     <p>
176     As long as you do not reload the
177     <code>jscoverage.html</code> page, the coverage report statistics are
178     cumulative. If you execute more JavaScript in the frame in the "Browser" tab (e.g., by clicking on a link to
179     another scripted page, or by reloading the frame containing a scripted
180     page) and switch to the "Summary" tab again,
181     the coverage report will combine the statistics from the previous report with any newly generated statistics.
182     Reloading <code>jscoverage.html</code> resets all code coverage statistics to zero.
183     </p>
184    
185     <h2>Example</h2>
186    
187     <p>
188     The JSCoverage distribution comes with a trivial example program in the <code>doc/example</code> directory.
189     You can view the file <code>doc/example/index.html</code> in your web browser to run the (uninstrumented) program.
190     To instrument this program, follow these steps:
191     </p>
192    
193     <h3>1. Instrumenting code</h3>
194    
195     <p>
196     From the main distribution directory, execute the command:
197     </p>
198    
199     <pre>
200     jscoverage doc/example doc/instrumented
201     </pre>
202    
203     <p>
204     This will create the directory <code>doc/instrumented</code> and
205     place an instrumented copy of the code from <code>doc/example</code> in <code>doc/instrumented</code>.
206     </p>
207    
208 siliconforks 115 <h3>2. Executing the instrumented code in a web browser</h3>
209 siliconforks 2
210     <p>
211     You can load the file <code>doc/instrumented/jscoverage.html</code> in your web browser and type
212     the URL for the instrumented code in the "URL" input field. Since a relative URL is accepted, you
213     can simply type <code>index.html</code> to load the page.
214     </p>
215    
216     <p>
217     Alternatively, you can append the URL to the query string of the
218     <code>jscoverage.html</code> URL; for example, if you are in the main JSCoverage
219     directory and the Firefox executable is in your <code>PATH</code>, you can load
220     the <code>jscoverage.html</code> frameset and the <code>index.html</code> page
221     all in one command line:
222     </p>
223    
224     <pre>
225     firefox "doc/instrumented/jscoverage.html?index.html"
226     </pre>
227    
228 siliconforks 197 <p><img src="screenshot2.png" alt="Screenshot"></p>
229 siliconforks 2
230     <p>
231     For this particular page, the JavaScript does not execute automatically:
232     you have to select one of the radio buttons to execute the code.
233     </p>
234    
235 siliconforks 197 <p><img src="screenshot3.png" alt="Screenshot"></p>
236 siliconforks 2
237 siliconforks 115 <h3>3. Generating a coverage report</h3>
238 siliconforks 2
239     <p>
240 siliconforks 14 Once you have executed the JavaScript code, you are instructed to click on the
241 siliconforks 2 "Summary" tab.
242     </p>
243    
244 siliconforks 197 <p><img src="screenshot4.png" alt="Screenshot"></p>
245 siliconforks 2
246     <p>
247 siliconforks 41 You can click the checkbox to show a list of statements missed during execution.
248 siliconforks 2 </p>
249    
250 siliconforks 197 <p><img src="screenshot5.png" alt="Screenshot"></p>
251 siliconforks 2
252 siliconforks 41 <p>
253     You can click one of the links to get a detailed view of a JavaScript source file.
254     </p>
255    
256 siliconforks 197 <p><img src="screenshot6.png" alt="Screenshot"></p>
257 siliconforks 41
258 siliconforks 14 <h2>Inverted mode</h2>
259    
260     <p>
261 siliconforks 41 In some situations it may be difficult to execute your code within the
262 siliconforks 14 JSCoverage "Browser" tab. For example, the code may assume that it is running in
263     the top-level browser window, generating errors if it is executed from within a
264     frame. JSCoverage has an alternative mode of operation, called <dfn>inverted
265 siliconforks 41 mode</dfn>, which may be useful in this case.
266 siliconforks 14 </p>
267    
268     <p>
269     Normally you load <code>jscoverage.html</code> in your web browser, and in its
270     "Browser" tab you launch your test code. In inverted mode, you do the
271     opposite: you load your test page directly in your web browser, and from there
272     you launch JSCoverage. To do this you need to add some code to your test page:
273     </p>
274    
275 siliconforks 198 <pre class="sh_javascript">
276     window.open('path/to/jscoverage.html');
277 siliconforks 14 </pre>
278    
279     <p>
280     The <code>"path/to/jscoverage.html"</code> should be a URL pointing to the
281     location of the <code>jscoverage.html</code> file (remember, this will be in the
282     top level of the <var>DESTINATION-DIRECTORY</var> you specified when running
283     the <code>jscoverage</code> executable).
284     </p>
285    
286     <p>
287     You can place this code wherever you like in your page: for example, you could
288     attach it to a button:
289     </p>
290    
291 siliconforks 198 <pre class="sh_html">
292     &lt;button onclick="window.open('path/to/jscoverage.html');"&gt;Coverage report&lt;/button&gt;
293 siliconforks 14 </pre>
294    
295     <p>
296 siliconforks 37 Note that you <em>must</em> use a <code>window.open</code> call; simply making a
297     link to <code>jscoverage.html</code> is not sufficient.
298     </p>
299    
300     <p>
301 siliconforks 14 An example is located in the <code>doc/example-inverted</code> directory.
302     You can instrument the code and launch the <code>index.html</code> page:
303     </p>
304    
305     <pre>
306     jscoverage doc/example-inverted doc/instrumented-inverted
307     firefox "doc/instrumented-inverted/index.html"
308     </pre>
309    
310     <p>
311     From this page, you select one of the radio buttons and then click the "Coverage
312     report" button to launch the JSCoverage report.
313     </p>
314    
315 siliconforks 115 <h2><code>jscoverage</code> command line options</h2>
316 siliconforks 19
317     <p>
318     The <code>jscoverage</code> program accepts the following options:
319     </p>
320    
321     <dl>
322     <dt><code>-h</code>, <code>--help</code>
323     <dd>Display a brief help message.
324     <dt><code>-V</code>, <code>--version</code>
325     <dd>Display the version of the program.
326     <dt><code>-v</code>, <code>--verbose</code>
327     <dd>Explain what is being done.
328 siliconforks 207 <dt><code>--encoding=<var>ENCODING</var></code>
329     <dd>Assume that all JavaScript files use the given character encoding. The
330     default is ISO-8859-1.
331 siliconforks 19 <dt><code>--exclude=<var>PATH</var></code>
332     <dd>The command
333     <pre>
334     jscoverage --exclude=<var>PATH</var> <var>SOURCE-DIRECTORY</var> <var>DESTINATION-DIRECTORY</var>
335     </pre>
336     copies <var>SOURCE-DIRECTORY</var> to <var>DESTINATION-DIRECTORY</var>
337     recursively, but does not copy <var>SOURCE-DIRECTORY</var>/<var>PATH</var>.
338 siliconforks 41 <var>PATH</var> must be a complete path relative to <var>SOURCE-DIRECTORY</var>.
339 siliconforks 19 <var>PATH</var> can be a file or a directory (in which case the directory and
340     its entire contents are skipped). This option may be given multiple times.
341 siliconforks 207 <dt><code>--no-highlight</code>
342     <dd>Do not perform syntax highlighting of JavaScript code.
343 siliconforks 19 <dt><code>--no-instrument=<var>PATH</var></code>
344     <dd>The command
345     <pre>
346 siliconforks 41 jscoverage --no-instrument=<var>PATH</var> <var>SOURCE-DIRECTORY</var> <var>DESTINATION-DIRECTORY</var>
347 siliconforks 19 </pre>
348     copies <var>SOURCE-DIRECTORY</var> to <var>DESTINATION-DIRECTORY</var>
349     recursively, but does not instrument any JavaScript code in
350     <var>SOURCE-DIRECTORY</var>/<var>PATH</var>. <var>PATH</var> must be a complete
351 siliconforks 59 path relative to <var>SOURCE-DIRECTORY</var>. <var>PATH</var> can be a
352 siliconforks 19 (JavaScript) file or a directory (in which case any JavaScript files located
353     anywhere underneath the directory are not instrumented). This option may be
354     given multiple times.
355     </dl>
356    
357     <h2>Query string options</h2>
358    
359     <p>
360     When accessing <code>jscoverage.html</code> in a web browser, you may provide a
361     query string consisting of options separated by ampersand (<code>&amp;</code>)
362     or semicolon (<code>;</code>). Any option not containing an equals sign
363     (<code>=</code>) is considered to be a URL which will be loaded in the "Browser"
364     tab.
365     </p>
366    
367     <dl>
368     <dt><code>u=<var>URL</var></code>, <code>url=<var>URL</var></code>
369     <dd>Load <var>URL</var> in the "Browser" tab. (This is the same as specifying
370     an option without an equals sign.)
371     <dt><code>m=<var>BOOLEAN</var></code>, <code>missing=<var>BOOLEAN</var></code>
372     <dd>Determines whether to initially display the "Missing" column in the "Summary"
373     tab. <var>BOOLEAN</var> can be
374 siliconforks 59 <code>true</code>, <code>t</code>, <code>yes</code>, <code>y</code>, <code>on</code>, <code>1</code>
375 siliconforks 19 (to display the "Missing" column), or
376     <code>false</code>, <code>f</code>, <code>no</code>, <code>n</code>, <code>off</code>, <code>0</code>
377 siliconforks 41 (to hide the "Missing" column). By default, the "Missing" column is not displayed.
378 siliconforks 19 </dl>
379    
380 siliconforks 115 <h2>Using the <code>jscoverage-server</code> program</h2>
381    
382     <p>
383 siliconforks 198 The <code>jscoverage-server</code> program is a simple web server. You can use
384     <code>jscoverage-server</code> to serve files from the <code>doc/example/</code>
385     directory:
386 siliconforks 115 </p>
387    
388     <pre>
389     cd doc/example
390     jscoverage-server --verbose
391     </pre>
392    
393     <p>
394 siliconforks 198 Once the server is running, you can access the JSCoverage web interface by
395     visiting the URL <code>http://127.0.0.1:8080/jscoverage.html</code>, and you can
396     load the <code>doc/example/index.html</code> file by entering
397     <code>index.html</code> in the "URL" input field. (Or you can do this all in
398     one step by loading the URL
399     <code>http://127.0.0.1:8080/jscoverage.html?index.html</code> in your web
400     browser.) The
401     <code>jscoverage-server</code> program automatically instruments any served
402 siliconforks 115 JavaScript code, so that code coverage data will be gathered as the code is
403     executed in your browser.
404     </p>
405    
406     <p>
407     The web interface is slightly different from that generated by the
408     <code>jscoverage</code> program: it has a new tab named "Store".
409     To store coverage data, click the "Store" tab.
410     </p>
411    
412 siliconforks 197 <p><img src="screenshot7.png" alt="Screenshot"></p>
413 siliconforks 115
414     <p>
415     When you click the "Store" button, the coverage data will be saved to a directory named <code>jscoverage-report/</code>.
416     You can view this stored report at any time by opening the file <code>jscoverage-report/jscoverage.html</code> in
417 siliconforks 198 your web browser - you don't need the <code>jscoverage-server</code> running to access it.
418 siliconforks 115 </p>
419    
420     <p>
421     If you use the "Store" tab again to store coverage data, the new data will be merged with
422     the previous data in the <code>jscoverage-report/</code> directory. This can be useful,
423     for instance, if you wish to run a set of tests in different browsers and generate an
424     aggregate report which combines the data for all of them.
425     </p>
426    
427     <p>
428     You can stop the server by running another instance of <code>jscoverage-server</code> with the
429     <code>--shutdown</code> option:
430     </p>
431    
432     <pre>
433     jscoverage-server --shutdown
434     </pre>
435    
436     <h2>Using <code>jscoverage-server --proxy</code></h2>
437    
438     <p>
439     To use <code>jscoverage-server</code> as a proxy server, use the <code>--proxy</code> option:
440     </p>
441    
442     <pre>
443     jscoverage-server --verbose --proxy
444     </pre>
445    
446     <p>
447     Configure your browser to use an HTTP proxy with address 127.0.0.1 and port 8080.
448     You can then generate code coverage data for a web page on the server <code>example.com</code>
449     by accessing the JSCoverage web interface at the special URL <code>http://example.com/jscoverage.html</code>.
450     Note that this URL is not provided by the <code>example.com</code> server; it is automatically generated
451     by the proxy server whenever a URL with path <code>/jscoverage.html</code> is requested.
452     </p>
453    
454     <h2><code>jscoverage-server</code> command line options</h2>
455    
456     <dl>
457     <dt><code>-h</code>, <code>--help</code>
458     <dd>Display a brief help message.
459     <dt><code>-V</code>, <code>--version</code>
460     <dd>Display the version of the program.
461     <dt><code>-v</code>, <code>--verbose</code>
462     <dd>Explain what is being done.
463     <dt><code>--document-root=<var>PATH</var></code>
464     <dd>Serve web content from the directory given by <var>PATH</var>. The default is
465     the current directory. This option may not be given with the <code>--proxy</code> option.
466 siliconforks 207 <dt><code>--encoding=<var>ENCODING</var></code>
467     <dd>Assume that all JavaScript files use the given character encoding. The
468     default is ISO-8859-1. Note that if you use the <code>--proxy</code> option, the
469     character encoding will be determined from the <code>charset</code> parameter in
470     the <code>Content-Type</code> HTTP header.
471 siliconforks 115 <dt><code>--ip-address=<var>ADDRESS</var></code>
472     <dd>Run the server on the IP address given by <var>ADDRESS</var>. The default is <code>127.0.0.1</code>. Specify
473     <code>0.0.0.0</code> to use any address.
474 siliconforks 207 <dt><code>--no-highlight</code>
475     <dd>Do not perform syntax highlighting of JavaScript code.
476 siliconforks 115 <dt><code>--no-instrument=<var>URL</var></code>
477     <dd>Do not instrument JavaScript code from <var>URL</var>. If you are running <code>jscoverage-server</code>
478     with the <code>--proxy</code> option, <var>URL</var> should be a full URL. For example:
479     <pre>
480     jscoverage-server --proxy --no-instrument=http://example.com/scripts/
481     </pre>
482     Without <code>--proxy</code>, <var>URL</var> should be only the path portion of a URL:
483     <pre>
484     jscoverage-server --no-instrument=/scripts/
485     </pre>
486     This option may be given multiple times.
487     <dt><code>--port=<var>PORT</var></code>
488     <dd>Run the server on the port given by <var>PORT</var>. The default is port 8080.
489     <dt><code>--proxy</code>
490     <dd>Run as a proxy server.
491     <dt><code>--report-dir=<var>PATH</var></code>
492     <dd>Use the directory given by <var>PATH</var> for storing coverage reports. The default is
493     <code>jscoverage-report/</code> in the current directory.
494     <dt><code>--shutdown</code>
495     <dd>Stop a running instance of the server.
496     </dl>
497    
498 siliconforks 158 <h2>Advanced topics</h2>
499    
500 siliconforks 198 <h3>Storing coverage reports programmatically</h3>
501    
502     <p>
503     If you are executing a test suite using <code>jscoverage-server</code>, you can
504     store a coverage report programmatically by having your test suite call the
505     <code>jscoverage_report</code> function (automatically generated by
506     <code>jscoverage-server</code>) after all your tests have finished running:
507     </p>
508    
509     <pre class="sh_javascript">
510     if (top.jscoverage_report) {
511     top.jscoverage_report();
512     }
513     </pre>
514    
515     <p>
516     You can specify the name of the directory in which to store the report by
517     passing the name as a parameter to the <code>jscoverage_report</code> function:
518     </p>
519    
520     <pre class="sh_javascript">
521     if (top.jscoverage_report) {
522     // determine the directory name based on the browser
523     var directory;
524     if (/MSIE/.test(navigator.userAgent)) {
525     directory = 'IE';
526     }
527     else {
528     directory = 'other';
529     }
530     top.jscoverage_report(directory);
531     }
532     </pre>
533    
534     <p>
535     This directory will be a subdirectory under the <code>jscoverage-report/</code>
536     directory (or whatever is specified with the <code>--report-dir</code> option).
537     Using the above example, the report would be stored to either
538     <code>jscoverage-report/IE/</code> or <code>jscoverage-report/other/</code>.
539     </p>
540    
541 siliconforks 201 <p>
542     It is not necessary that your test suite be executed within the
543     <code>jscoverage.html</code> web interface to store a coverage report. The URL
544     of the test suite can simply be loaded directly in a web browser.
545     </p>
546    
547 siliconforks 158 <h3>Conditional directives</h3>
548    
549     <p>
550     Sometimes you may wish to exclude certain lines of code from coverage
551     statistics. Some lines of code may be executed only in certain browsers; other
552 siliconforks 198 lines should never be executed at all (they may be present only to detect
553 siliconforks 158 programming errors). You can use specially formatted comments in your code,
554     called <dfn>conditional directives</dfn>, to tell JSCoverage when to exclude
555     those lines from coverage statistics. These lines will be ignored in the
556     JSCoverage "Summary" tab; in the "Source" tab, these lines will be indicated
557     with the color yellow.
558     </p>
559    
560     <p>
561     Conditional directives take the following form:
562     </p>
563    
564     <pre class="sh_javascript">
565     //#JSCOVERAGE_IF <var>CONDITION</var>
566     ...
567     //#JSCOVERAGE_ENDIF
568     </pre>
569    
570     <p>
571     The <var>CONDITION</var> is an ordinary JavaScript expression; if this
572     expression evaluates to <code>true</code>, then the lines of code between the
573     <code>//#JSCOVERAGE_IF</code> and <code>//#JSCOVERAGE_ENDIF</code> directives are
574     included in coverage statistics; otherwise, they are excluded from coverage
575     statistics.
576     </p>
577    
578     <p>
579     In order to be recognized as a conditional directive, the comment must be
580     formatted exactly as shown: it must be a line comment starting with <code>//</code>,
581     it must start in the first column, and it must be followed by <code>#JSCOVERAGE_IF</code>
582     or <code>#JSCOVERAGE_ENDIF</code> in uppercase letters with no intervening white space.
583     </p>
584    
585     <p>
586     For example, if you have some code in an <code>if</code> statement which is
587     executed only in certain browsers, you can usually just repeat the condition in
588     a <code>//#JSCOVERAGE_IF</code> directive:
589     </p>
590    
591     <pre class="sh_javascript">
592     if (window.ActiveXObject) {
593     //#JSCOVERAGE_IF window.ActiveXObject
594     return new ActiveXObject('Msxml2.XMLHTTP');
595     //#JSCOVERAGE_ENDIF
596     }
597     </pre>
598    
599     <p>
600     Alternatively, it may be easier to diagnose problems if you specify exactly
601     which browsers you expect to execute the code in the conditional:
602     </p>
603    
604     <pre class="sh_javascript">
605     if (window.ActiveXObject) {
606     //#JSCOVERAGE_IF /MSIE/.test(navigator.userAgent)
607     return new ActiveXObject('Msxml2.XMLHTTP');
608     //#JSCOVERAGE_ENDIF
609     }
610     </pre>
611    
612     <p>
613 siliconforks 196 To exclude code from coverage statistics unconditionally, you can use <code>//#JSCOVERAGE_IF 0</code> or
614     <code>//#JSCOVERAGE_IF false</code>:
615 siliconforks 158 </p>
616    
617     <pre class="sh_javascript">
618     function f(s) {
619     if (typeof(s) !== 'string') {
620     //#JSCOVERAGE_IF 0
621     throw 'function f requires a string argument';
622     //#JSCOVERAGE_ENDIF
623     }
624     }
625     </pre>
626    
627 siliconforks 201 <p>
628     Currently, conditional directives are ignored in stored coverage reports.
629     </p>
630    
631 siliconforks 2 <h2>Caveats</h2>
632    
633     <ul>
634     <li>JSCoverage adds instrumentation to JavaScript code, which will slow down execution speed.
635     Expect instrumented code to take at least twice as much time to run.
636     <li>JSCoverage currently instruments only <code>.js</code> files; it does not instrument code in <code>&lt;script&gt;</code>
637     elements in HTML files.
638     <li>HTML files must use relative URLs to reference scripts. If you use an absolute URL, your page will reference
639     the original uninstrumented script rather than the instrumented one, and no code coverage data will be collected.
640     <li>JSCoverage instruments physical lines of code rather than logical JavaScript statements; it works bests with code
641     that has exactly one statement per line. If you put multiple statements on a line, or split a line across two or more
642     statements, you may get strange results.
643     <li>JSCoverage uses frames. Some web pages that use frames may not function properly when run under JSCoverage, especially
644     those which try to access the top-level frame (<code>window.top</code>, <code>target="_top"</code>, etc.).
645 siliconforks 198 <li>JSCoverage is distributed without any warranty. See the <a href="license.html">license</a> for more details.
646 siliconforks 2 </ul>
647    
648     <address>
649 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>
650 siliconforks 158 Last updated September 12, 2008<br>
651 siliconforks 2 <a href="mailto:jscoverage@siliconforks.com">jscoverage@siliconforks.com</a>
652     </address>
653    
654     </body>
655     </html>

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