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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 2 <h2>Installing JSCoverage</h2>
43    
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     <dt><code>--exclude=<var>PATH</var></code>
329     <dd>The command
330     <pre>
331     jscoverage --exclude=<var>PATH</var> <var>SOURCE-DIRECTORY</var> <var>DESTINATION-DIRECTORY</var>
332     </pre>
333     copies <var>SOURCE-DIRECTORY</var> to <var>DESTINATION-DIRECTORY</var>
334     recursively, but does not copy <var>SOURCE-DIRECTORY</var>/<var>PATH</var>.
335 siliconforks 41 <var>PATH</var> must be a complete path relative to <var>SOURCE-DIRECTORY</var>.
336 siliconforks 19 <var>PATH</var> can be a file or a directory (in which case the directory and
337     its entire contents are skipped). This option may be given multiple times.
338     <dt><code>--no-instrument=<var>PATH</var></code>
339     <dd>The command
340     <pre>
341 siliconforks 41 jscoverage --no-instrument=<var>PATH</var> <var>SOURCE-DIRECTORY</var> <var>DESTINATION-DIRECTORY</var>
342 siliconforks 19 </pre>
343     copies <var>SOURCE-DIRECTORY</var> to <var>DESTINATION-DIRECTORY</var>
344     recursively, but does not instrument any JavaScript code in
345     <var>SOURCE-DIRECTORY</var>/<var>PATH</var>. <var>PATH</var> must be a complete
346 siliconforks 59 path relative to <var>SOURCE-DIRECTORY</var>. <var>PATH</var> can be a
347 siliconforks 19 (JavaScript) file or a directory (in which case any JavaScript files located
348     anywhere underneath the directory are not instrumented). This option may be
349     given multiple times.
350     </dl>
351    
352     <h2>Query string options</h2>
353    
354     <p>
355     When accessing <code>jscoverage.html</code> in a web browser, you may provide a
356     query string consisting of options separated by ampersand (<code>&amp;</code>)
357     or semicolon (<code>;</code>). Any option not containing an equals sign
358     (<code>=</code>) is considered to be a URL which will be loaded in the "Browser"
359     tab.
360     </p>
361    
362     <dl>
363     <dt><code>u=<var>URL</var></code>, <code>url=<var>URL</var></code>
364     <dd>Load <var>URL</var> in the "Browser" tab. (This is the same as specifying
365     an option without an equals sign.)
366     <dt><code>m=<var>BOOLEAN</var></code>, <code>missing=<var>BOOLEAN</var></code>
367     <dd>Determines whether to initially display the "Missing" column in the "Summary"
368     tab. <var>BOOLEAN</var> can be
369 siliconforks 59 <code>true</code>, <code>t</code>, <code>yes</code>, <code>y</code>, <code>on</code>, <code>1</code>
370 siliconforks 19 (to display the "Missing" column), or
371     <code>false</code>, <code>f</code>, <code>no</code>, <code>n</code>, <code>off</code>, <code>0</code>
372 siliconforks 41 (to hide the "Missing" column). By default, the "Missing" column is not displayed.
373 siliconforks 19 </dl>
374    
375 siliconforks 115 <h2>Using the <code>jscoverage-server</code> program</h2>
376    
377     <p>
378 siliconforks 198 The <code>jscoverage-server</code> program is a simple web server. You can use
379     <code>jscoverage-server</code> to serve files from the <code>doc/example/</code>
380     directory:
381 siliconforks 115 </p>
382    
383     <pre>
384     cd doc/example
385     jscoverage-server --verbose
386     </pre>
387    
388     <p>
389 siliconforks 198 Once the server is running, you can access the JSCoverage web interface by
390     visiting the URL <code>http://127.0.0.1:8080/jscoverage.html</code>, and you can
391     load the <code>doc/example/index.html</code> file by entering
392     <code>index.html</code> in the "URL" input field. (Or you can do this all in
393     one step by loading the URL
394     <code>http://127.0.0.1:8080/jscoverage.html?index.html</code> in your web
395     browser.) The
396     <code>jscoverage-server</code> program automatically instruments any served
397 siliconforks 115 JavaScript code, so that code coverage data will be gathered as the code is
398     executed in your browser.
399     </p>
400    
401     <p>
402     The web interface is slightly different from that generated by the
403     <code>jscoverage</code> program: it has a new tab named "Store".
404     To store coverage data, click the "Store" tab.
405     </p>
406    
407 siliconforks 197 <p><img src="screenshot7.png" alt="Screenshot"></p>
408 siliconforks 115
409     <p>
410     When you click the "Store" button, the coverage data will be saved to a directory named <code>jscoverage-report/</code>.
411     You can view this stored report at any time by opening the file <code>jscoverage-report/jscoverage.html</code> in
412 siliconforks 198 your web browser - you don't need the <code>jscoverage-server</code> running to access it.
413 siliconforks 115 </p>
414    
415     <p>
416     If you use the "Store" tab again to store coverage data, the new data will be merged with
417     the previous data in the <code>jscoverage-report/</code> directory. This can be useful,
418     for instance, if you wish to run a set of tests in different browsers and generate an
419     aggregate report which combines the data for all of them.
420     </p>
421    
422     <p>
423     You can stop the server by running another instance of <code>jscoverage-server</code> with the
424     <code>--shutdown</code> option:
425     </p>
426    
427     <pre>
428     jscoverage-server --shutdown
429     </pre>
430    
431     <h2>Using <code>jscoverage-server --proxy</code></h2>
432    
433     <p>
434     To use <code>jscoverage-server</code> as a proxy server, use the <code>--proxy</code> option:
435     </p>
436    
437     <pre>
438     jscoverage-server --verbose --proxy
439     </pre>
440    
441     <p>
442     Configure your browser to use an HTTP proxy with address 127.0.0.1 and port 8080.
443     You can then generate code coverage data for a web page on the server <code>example.com</code>
444     by accessing the JSCoverage web interface at the special URL <code>http://example.com/jscoverage.html</code>.
445     Note that this URL is not provided by the <code>example.com</code> server; it is automatically generated
446     by the proxy server whenever a URL with path <code>/jscoverage.html</code> is requested.
447     </p>
448    
449     <h2><code>jscoverage-server</code> command line options</h2>
450    
451     <dl>
452     <dt><code>-h</code>, <code>--help</code>
453     <dd>Display a brief help message.
454     <dt><code>-V</code>, <code>--version</code>
455     <dd>Display the version of the program.
456     <dt><code>-v</code>, <code>--verbose</code>
457     <dd>Explain what is being done.
458     <dt><code>--document-root=<var>PATH</var></code>
459     <dd>Serve web content from the directory given by <var>PATH</var>. The default is
460     the current directory. This option may not be given with the <code>--proxy</code> option.
461     <dt><code>--ip-address=<var>ADDRESS</var></code>
462     <dd>Run the server on the IP address given by <var>ADDRESS</var>. The default is <code>127.0.0.1</code>. Specify
463     <code>0.0.0.0</code> to use any address.
464     <dt><code>--no-instrument=<var>URL</var></code>
465     <dd>Do not instrument JavaScript code from <var>URL</var>. If you are running <code>jscoverage-server</code>
466     with the <code>--proxy</code> option, <var>URL</var> should be a full URL. For example:
467     <pre>
468     jscoverage-server --proxy --no-instrument=http://example.com/scripts/
469     </pre>
470     Without <code>--proxy</code>, <var>URL</var> should be only the path portion of a URL:
471     <pre>
472     jscoverage-server --no-instrument=/scripts/
473     </pre>
474     This option may be given multiple times.
475     <dt><code>--port=<var>PORT</var></code>
476     <dd>Run the server on the port given by <var>PORT</var>. The default is port 8080.
477     <dt><code>--proxy</code>
478     <dd>Run as a proxy server.
479     <dt><code>--report-dir=<var>PATH</var></code>
480     <dd>Use the directory given by <var>PATH</var> for storing coverage reports. The default is
481     <code>jscoverage-report/</code> in the current directory.
482     <dt><code>--shutdown</code>
483     <dd>Stop a running instance of the server.
484     </dl>
485    
486 siliconforks 158 <h2>Advanced topics</h2>
487    
488 siliconforks 198 <h3>Storing coverage reports programmatically</h3>
489    
490     <p>
491     If you are executing a test suite using <code>jscoverage-server</code>, you can
492     store a coverage report programmatically by having your test suite call the
493     <code>jscoverage_report</code> function (automatically generated by
494     <code>jscoverage-server</code>) after all your tests have finished running:
495     </p>
496    
497     <pre class="sh_javascript">
498     if (top.jscoverage_report) {
499     top.jscoverage_report();
500     }
501     </pre>
502    
503     <p>
504     You can specify the name of the directory in which to store the report by
505     passing the name as a parameter to the <code>jscoverage_report</code> function:
506     </p>
507    
508     <pre class="sh_javascript">
509     if (top.jscoverage_report) {
510     // determine the directory name based on the browser
511     var directory;
512     if (/MSIE/.test(navigator.userAgent)) {
513     directory = 'IE';
514     }
515     else {
516     directory = 'other';
517     }
518     top.jscoverage_report(directory);
519     }
520     </pre>
521    
522     <p>
523     This directory will be a subdirectory under the <code>jscoverage-report/</code>
524     directory (or whatever is specified with the <code>--report-dir</code> option).
525     Using the above example, the report would be stored to either
526     <code>jscoverage-report/IE/</code> or <code>jscoverage-report/other/</code>.
527     </p>
528    
529 siliconforks 158 <h3>Conditional directives</h3>
530    
531     <p>
532     Sometimes you may wish to exclude certain lines of code from coverage
533     statistics. Some lines of code may be executed only in certain browsers; other
534 siliconforks 198 lines should never be executed at all (they may be present only to detect
535 siliconforks 158 programming errors). You can use specially formatted comments in your code,
536     called <dfn>conditional directives</dfn>, to tell JSCoverage when to exclude
537     those lines from coverage statistics. These lines will be ignored in the
538     JSCoverage "Summary" tab; in the "Source" tab, these lines will be indicated
539     with the color yellow.
540     </p>
541    
542     <p>
543     Conditional directives take the following form:
544     </p>
545    
546     <pre class="sh_javascript">
547     //#JSCOVERAGE_IF <var>CONDITION</var>
548     ...
549     //#JSCOVERAGE_ENDIF
550     </pre>
551    
552     <p>
553     The <var>CONDITION</var> is an ordinary JavaScript expression; if this
554     expression evaluates to <code>true</code>, then the lines of code between the
555     <code>//#JSCOVERAGE_IF</code> and <code>//#JSCOVERAGE_ENDIF</code> directives are
556     included in coverage statistics; otherwise, they are excluded from coverage
557     statistics.
558     </p>
559    
560     <p>
561     In order to be recognized as a conditional directive, the comment must be
562     formatted exactly as shown: it must be a line comment starting with <code>//</code>,
563     it must start in the first column, and it must be followed by <code>#JSCOVERAGE_IF</code>
564     or <code>#JSCOVERAGE_ENDIF</code> in uppercase letters with no intervening white space.
565     </p>
566    
567     <p>
568     For example, if you have some code in an <code>if</code> statement which is
569     executed only in certain browsers, you can usually just repeat the condition in
570     a <code>//#JSCOVERAGE_IF</code> directive:
571     </p>
572    
573     <pre class="sh_javascript">
574     if (window.ActiveXObject) {
575     //#JSCOVERAGE_IF window.ActiveXObject
576     return new ActiveXObject('Msxml2.XMLHTTP');
577     //#JSCOVERAGE_ENDIF
578     }
579     </pre>
580    
581     <p>
582     Alternatively, it may be easier to diagnose problems if you specify exactly
583     which browsers you expect to execute the code in the conditional:
584     </p>
585    
586     <pre class="sh_javascript">
587     if (window.ActiveXObject) {
588     //#JSCOVERAGE_IF /MSIE/.test(navigator.userAgent)
589     return new ActiveXObject('Msxml2.XMLHTTP');
590     //#JSCOVERAGE_ENDIF
591     }
592     </pre>
593    
594     <p>
595 siliconforks 196 To exclude code from coverage statistics unconditionally, you can use <code>//#JSCOVERAGE_IF 0</code> or
596     <code>//#JSCOVERAGE_IF false</code>:
597 siliconforks 158 </p>
598    
599     <pre class="sh_javascript">
600     function f(s) {
601     if (typeof(s) !== 'string') {
602     //#JSCOVERAGE_IF 0
603     throw 'function f requires a string argument';
604     //#JSCOVERAGE_ENDIF
605     }
606     }
607     </pre>
608    
609 siliconforks 2 <h2>Caveats</h2>
610    
611     <ul>
612     <li>JSCoverage adds instrumentation to JavaScript code, which will slow down execution speed.
613     Expect instrumented code to take at least twice as much time to run.
614     <li>JSCoverage currently instruments only <code>.js</code> files; it does not instrument code in <code>&lt;script&gt;</code>
615     elements in HTML files.
616     <li>HTML files must use relative URLs to reference scripts. If you use an absolute URL, your page will reference
617     the original uninstrumented script rather than the instrumented one, and no code coverage data will be collected.
618     <li>JSCoverage instruments physical lines of code rather than logical JavaScript statements; it works bests with code
619     that has exactly one statement per line. If you put multiple statements on a line, or split a line across two or more
620     statements, you may get strange results.
621     <li>JSCoverage uses frames. Some web pages that use frames may not function properly when run under JSCoverage, especially
622     those which try to access the top-level frame (<code>window.top</code>, <code>target="_top"</code>, etc.).
623 siliconforks 198 <li>JSCoverage is distributed without any warranty. See the <a href="license.html">license</a> for more details.
624 siliconforks 2 </ul>
625    
626     <address>
627 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>
628 siliconforks 158 Last updated September 12, 2008<br>
629 siliconforks 2 <a href="mailto:jscoverage@siliconforks.com">jscoverage@siliconforks.com</a>
630     </address>
631    
632     </body>
633     </html>

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