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2 <head>
3 <title>dygraphs JavaScript Visualization Library</title>
4 <!--[if IE]>
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7 <script type="text/javascript" src="dygraph-combined.js"></script>
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48 </head>
49<body>
50
51<div id="nav">
52<ul>
53<li><b>Documentation</b>
54 <ul>
55 <li><a href="#demo">Demo</a>
56 <li><a href="#usage">Usage</a>
57 <li><a href="#stock">Stock chart</a>
58 <li><a href="#options">Options Reference</a>
59 <li><a href="#policy">Data Policy</a>
60 </ul>
61
62<li><b>Project</b>
63 <ul>
64 <li><a href="http://github.com/danvk/dygraphs">Source</a>
65 <li><a href="http://code.google.com/p/dygraphs/issues/">Issues</a>
66 <li><a href="http://code.google.com/p/dygraphs/issues/entry">Report Bug</a>
67 <li><a href="mailto:danvdk [at] gmail">Contact</a>
68 </ul>
69
70
71<li><b>Gallery</b>
72 <ul>
73 <li><a href="tests/demo.html">Basic Demo</a>
74 <li><a href="tests/gviz.html">GViz Demo</a>
75 <li><a href="tests/plotter.html">Equation Plotter</a>
76 <li><a href="tests/perf.html">Performance Test</a>
77
78 <li><a href="tests/label-div.html">Labels in a DIV</a>
79 <li><a href="tests/numeric-axis.html">Numeric Axis</a>
80 <li><a href="tests/draw-points.html">Dotted Points</a>
81
82 <li><a href="tests/native-format.html">Native Format</a>
83 <li><a href="tests/grid_dot.html">Crazy Styles</a>
84 <li><a href="tests/spacing.html">Tick spacing</a>
85 <li><a href="tests/callback.html">Callbacks</a>
86 <li><a href="tests/crosshair.html">Crosshairs</a>
87 <li><a href="tests/hourly.html">Hourly/Minutely data</a>
88
89 <li><a href="tests/isolated-points.html">Isolated Points</a>
90 <li><a href="tests/missing-data.html">Missing Data</a>
91
92 <li><a href="tests/border.html">Bordered chart</a>
93 <li><a href="tests/custom-bars.html">Custom Bars</a>
94 <li><a href="tests/customLabel.html">Custom Label Styles</a>
95 <li><a href="tests/dygraph.html">Minimal Example</a>
96 <li><a href="tests/negative.html">Negative Numbers</a>
97 <li><a href="tests/noise.html">Noisy Data</a>
98 <li><a href="tests/two-series.html">Multiple Series</a>
99 </ul>
100</ul>
101</div>
102
103<div id="content">
104<p><span style="font-size:28pt;">dygraphs JavaScript Visualization Library</span><br/>
105<a href="http://github.com/danvk/dygraphs">http://github.com/danvk/dygraphs</a><br/>
106See <a href="tests/">gallery</a> and <a href="http://code.google.com/p/dygraphs/issues/">open issues</a></p>
107
108<p>The dygraphs JavaScript library produces produces interactive, zoomable charts of time series. It is designed to display dense data sets and enable users to explore and interpret them.</p>
109
110<h3>Features</h3>
111<ul>
112 <li>Plots time series without using an external server or Flash</li>
113 <li>Supports error bands around data series</li>
114 <li>Displays values on mouseover (this makes it easily discoverable)</li>
115 <li>Interactive zoom</li>
116 <li>Adjustable averaging period</li>
117 <li>Customizable click-through actions</li>
118 <li>Compatible with the Google Visualization API</li>
119 <li>Works in Internet Explorer (using excanvas)</li>
120 <li>Intelligent defaults make it easy to use</li>
121 <li>Lightweight (45kb) and responsive</li>
122</ul>
123
124<a name="demo"><h2>Demo</h2>
125<p><font size=-1>(Mouse over to highlight individual values. Click and drag to zoom. Double-click to zoom back out. Change the number and hit enter to adjust the averaging period.)</font></p>
126<div id="title" style="width:800px; text-align:center; font-weight: bold; font-size: 125%;">Temperatures in New York vs. San Francisco</div>
127<div id="demodiv" style="width:800px; height:320px;"></div>
128<script type="text/javascript">
129 g = new Dygraph(
130 document.getElementById("demodiv"),
131 "ny-vs-sf.txt",
132 {
133 rollPeriod: 14,
134 showRoller: true,
135 customBars: true,
136 yAxisLabelWidth: 30
137 }
138 );
139</script>
140
141<p>Some things to notice:</p>
142<ul>
143<li>There's less seasonal temperature variation in SF than in NY.
144<li>The difference is about 15&deg; F for SF vs. 50&deg; F for NY.
145<li>The daily data (set rolling period to 1) is quite noisy and hides this conclusion.
146<li>Using a 14-day moving average makes it clearer. A 100-day rolling period averages out nearly all the specifics from the data.
147<li>There's a gap in the data for SF, when the weather station was down (zoom into October 2007 to see it).
148<li>The bands around each point indicate average highs and lows.
149<li>There is a <i>lot</i> of data in this chart: low, average and high for each city on each day of a three year period &asymp; 6000 data points in all.
150</ul>
151
152<p>For more demos, browse the dygraph <a href="tests/">tests</a> directory.</p>
153
154<a name="usage"><h2>Usage</h2>
155
156<p>To use dygraphs, include the <code>dygraph-combined.js</code> JavaScript file and instantiate a <code>Dygraph</code> object.</p>
157
158<p>Here's a basic example to get things started:</p>
159
160<table>
161 <tr><th>HTML</th>
162 <td rowspan=2><img src=arrow.gif /></td>
163 <th>Output</th></tr>
164<tr>
165<td valign=top><pre>
166&lt;html&gt;
167&lt;head&gt;
168&lt;script type="text/javascript"
169 src="dygraph-combined.js"&gt;&lt;/script&gt;
170&lt;/head&gt;
171&lt;body&gt;
172&lt;div id="graphdiv"&gt;&lt;/div&gt;
173&lt;script type="text/javascript"&gt;
174 g = new Dygraph(
175 // containing div
176 document.getElementById("graphdiv"),
177 // CSV or path to a CSV file.
178 "Date,Temperature\n" +
179 "2008-05-07,75\n" +
180 "2008-05-08,70\n" +
181 "2008-05-09,80\n"
182 );
183&lt;/script&gt;
184&lt;/body&gt;
185&lt;/html&gt;
186</pre>
187</td><td valign=top>
188 <div id="graphdiv"></div>
189</td></tr></table>
190
191<script type="text/javascript">
192 g1 = new Dygraph(
193 document.getElementById("graphdiv"), // containing div
194 "Date,Temperature\n" + // CSV or path to a CSV file.
195 "2008-05-07,75\n" +
196 "2008-05-08,70\n" +
197 "2008-05-09,80\n"
198 );
199</script>
200
201<p>In order to keep this example self-contained, the second parameter is raw CSV data. The dygraphs library parses this data (including column headers), resizes the its container to a reasonable default, calculates appropriate axis ranges and tick marks and draws the graph.</p>
202
203<p>In most applications, it makes more sense to include a CSV file instead. If the second parameter to the constructor doesn't contain a newline, it will be interpreted as the path to a CSV file. The Dygraph will perform an XMLHttpRequest to retrieve this file and display the data when it becomes available. Make sure your CSV file is readable and serving from a place that understands XMLHttpRequest's! In particular, you cannot specify a CSV file using <code>"file:///"</code>. Here's an example: (data from <a href="http://www.wunderground.com/history/airport/KNUQ/2007/1/1/CustomHistory.html?dayend=31&monthend=12&yearend=2007&req_city=NA&req_state=NA&req_statename=NA">Weather Underground</a>)</p>
204
205<table>
206 <tr><th>HTML</th>
207 <td rowspan=2><img src=arrow.gif /></td>
208 <th>Output</th></tr>
209<tr>
210<td valign=top><pre>
211&lt;html&gt;
212&lt;head&gt;
213&lt;script type="text/javascript"
214 src="dygraph-combined.js"&gt;&lt;/script&gt;
215&lt;/head&gt;
216&lt;body&gt;
217&lt;div id="graphdiv"
218 style="width:500px; height:300px;"&gt;&lt;/div&gt;
219&lt;script type="text/javascript"&gt;
220 new Dygraph(
221 document.getElementById("graphdiv"),
222 "temperatures.csv", // path to CSV file
223 {} // options
224 );
225&lt;/script&gt;
226&lt;/body&gt;
227&lt;/html&gt;
228</pre>
229</td><td valign=top>
230 <div id="graphdiv2" style="width:500px; height:300px;"></div>
231</td></tr></table>
232
233<script type="text/javascript">
234 g2 = new Dygraph(
235 document.getElementById("graphdiv2"),
236 "temperatures.csv", {}
237 );
238</script>
239
240<p>Click <a href="temperatures.csv">here</a> to view the <code>temperatures.csv</code> file. There are a few things to note here:</p>
241
242<ul>
243 <li>The Dygraph sent off an XHR to get the temperatures.csv file.</li>
244 <li>The labels were taken from the first line of <code>temperatures.csv</code>, which is <code>Date,High,Low</code>.</li>
245 <li>The Dygraph automatically chose two different, easily-distinguishable colors for the two data series.</li>
246 <li>The labels on the x-axis have switched from days to months. If you zoom in, they'll switch to weeks and then days.</li>
247 <li>Some heuristics are used to determine a good vertical range for the data. The idea is to make all the data visible and have human-friendly values on the axis (i.e. 200 instead of 193.4). Generally this works well.</li>
248 <li>The data is very spiky. A moving average would be easier to interpret.</li>
249</ul>
250
251<p>This problem can be fixed by specifying the appropriate options in the "additional options" parameter to the Dygraph constructor. To set the number of days for a moving average, use the <code>rollPeriod</code> option. Here's how it's done:</p>
252
253<table>
254 <tr><th>HTML</th>
255 <td rowspan=2><img src=arrow.gif /></td>
256 <th>Output</th></tr>
257<tr>
258<td valign=top><pre>
259&lt;html&gt;
260&lt;head&gt;
261&lt;script type="text/javascript"
262 src="dygraph-combined.js"&gt;&lt;/script&gt;
263&lt;/head&gt;
264&lt;body&gt;
265&lt;div id="graphdiv"
266 style="width:500px; height:300px;"&gt;&lt;/div&gt;
267&lt;script type="text/javascript"&gt;
268 g = new Dygraph(
269 document.getElementById("graphdiv"),
270 "temperatures.csv",
271 { rollPeriod: 7,
272 showRoller: true,
273 }
274 );
275&lt;/script&gt;
276&lt;/body&gt;
277&lt;/html&gt;
278</pre>
279</td><td valign=top>
280 <div id="graphdiv3" style="width:500px; height:300px;"></div>
281</td></tr></table>
282
283<script type="text/javascript">
284 g3 = new Dygraph(
285 document.getElementById("graphdiv3"),
286 "temperatures.csv",
287 { rollPeriod: 7,
288 showRoller: true });
289</script>
290
291<p>A rolling average can be set using the text box in the lower left-hand corner of the graph (the showRoller attribute is what makes this appear). Also note that we've explicitly set the size of the chart div.</p>
292
293<h2>Error Bars</h2>
294<p>Another significant feature of the dygraphs library is the ability to display error bars around data series. One standard deviation must be specified for each data point. A +/-<i>n</i> sigma band will be drawn around the data series at that point. If a moving average is being displayed, dygraphs will compute the standard deviation of the average at each point. (i.e. <i>&sigma;</i> = sqrt((<i>&sigma;_1</i>^2 + <i>&sigma;_2</i>^2 + ... + <i>&sigma;_n</i>^2)/<i>n</i>))</p>
295
296<p>Here's a demonstration. There are two data series. One is <code>N(100,10)</code> with a standard deviation of 10 specified at each point. The other is <code>N(80,20)</code> with a standard deviation of 20 specified at each point. The CSV file was generated using Octave and can be viewed <a href="twonormals.csv">here</a>.</p>
297
298<table>
299 <tr><th>HTML</th>
300 <td rowspan=2><img src=arrow.gif /></td>
301 <th>Output</th></tr>
302<tr>
303<td valign=top><pre>
304&lt;html&gt;
305&lt;head&gt;
306&lt;script type="text/javascript"
307 src="combined.js"&gt;&lt;/script&gt;
308&lt;/head&gt;
309&lt;body&gt;
310&lt;div id="graphdiv"
311 style="width:600px; height:300px;"
312 &gt;&lt;/div&gt;
313&lt;script type="text/javascript"&gt;
314$ = document.getElementById;
315g = new Dygraph(
316 $("graphdiv"),
317 "twonormals.csv",
318 { rollPeriod: 7,
319 showRoller: true,
320 errorBars: true,
321 valueRange: [50,125]
322 }
323);
324&lt;/script&gt;
325&lt;/body&gt;
326&lt;/html&gt;
327</pre>
328</td><td valign=top>
329 <div id="graphdiv4" style="width:600px; height:300px;"></div>
330</td></tr></table>
331
332<script type="text/javascript">
333$ = document.getElementById;
334new Dygraph(
335 document.getElementById("graphdiv4"),
336 "twonormals.csv",
337 { rollPeriod: 14,
338 showRoller: true,
339 errorBars: true,
340 valueRange: [50, 125]
341 }
342);
343</script>
344
345<p>Things to note here:</p>
346<ul>
347 <li>The <b>errorBars</b> option affects both the interpretation of the CSV file and the display of the graph. When <b>errorBars</b> is set to true, each line is interpreted as <i>YYYYMMDD</i>,<i>A</i>,<i>sigma_A</i>,<i>B</i>,<i>sigma_B</i>,...</li>
348 <li>The first line of the CSV file doesn't mention the error columns. In this case, it's just "Date,Series1,Series2".</li>
349 <li>The averaging visibly affects the error bars. This is most clear if you crank up the rolling period to something like 100 days. For the earliest dates, there won't be 100 data points to average so the signal will be noisier. The error bars get smaller like sqrt(N) going forward in time until there's a full 100 points to average.</li>
350 <li>The error bars are partially transparent. This can be seen when they overlap one another.</li>
351</ul>
352
353<a name="stock"><h2>One last demo</h2>
354
355<p>This chart shows monthly closes of the Dow Jones Industrial Average, both in nominal and real (i.e. adjusted for inflation) dollars. The shaded areas show its monthly high and low. CPI values with a base from 1982-84 are used to adjust for inflation.</p>
356
357<div id=dow_chart style="width:900px; height:350px;"></div>
358<script type="text/javascript">
359 // From http://www.econstats.com/eqty/eq_d_mi_3.csv
360 dow = new Dygraph(
361 document.getElementById('dow_chart'),
362 "dow.txt",
363 {
364 showRoller: true,
365 customBars: true,
366 labelsKMB: true });
367</script>
368<!--
369
370Here is a script to regenerate the Dow Jones plot:
371
372# Get unadjusted DJIA data in a nice format:
373curl -O http://www.econstats.com/eqty/eq_d_mi_3.csv
374sed '1,17d' eq_d_mi_3.csv | cut -d, -f1,6 | perl -pe 's/(\d{4}-\d\d)-\d\d/$1/g' | perl -pe 's/, */\t/' | grep -v 'na' | perl -ne 'chomp; ($m,$v) = split/\t/; $close{$m} = $v; if ($low{$m} == 0 || $v < $low{$m}) { $low{$m}=$v } if ($v > $high{$m}) { $high{$m} = $v } END { for $x(sort keys %close) { print "$x\t$low{$x}\t$close{$x}\t$high{$x}\n" } } ' > monthly-djia.tsv
375
376# Fetch and format the CPI data:
377curl 'http://data.bls.gov/PDQ/servlet/SurveyOutputServlet?series_id=CUUR0000SA0&years_option=all_years&periods_option=all_periods&output_type=column&output_format=text&delimiter=comma' > cpi-u.txt
378sed '1,/Series Id,Year,/d' cpi-u.txt | sed '/^$/,$d' | cut -d, -f2,3,4 | perl -ne 'print if /,M(0[0-9]|1[012]),/' | perl -pe 's/(\d{4}),M(\d{2}),/$1-$2\t/g' > cpi-u.tsv
379
380# Merge:
381join -t' ' cpi-u.tsv monthly-djia.tsv > annotated-djia.tsv
382perl -ne 'BEGIN{print "Month,Nominal,Real\n"} chomp; ($m,$cpi,$low,$close,$high) = split /\t/; $cpi /= 100.0; print "$m-15,$low;$close;$high,",($low/$cpi),";",($close/$cpi),";",($high/$cpi),"\n"' annotated-djia.tsv > dow.txt
383
384-->
385
386
387<a name="options">
388<h2>Other Options</h2>
389<p>These are the options that can be passed in through the optional third parameter of the Dygraph constructor. To see demonstrations of many of these options, browse the <a href="tests/">dygraphs tests</a> directory.</p>
390
391<table class=thinborder width=900>
392 <tr><th>Name</th><th>Sample Value</th><th>Description</th></tr>
393 <tr>
394 <td><b>includeZero</b></td>
395 <td><code>true, false</code></td>
396 <td>Usually, dygraphs will use the range of the data plus some padding to
397 set the range of the y-axis. If this option is set, the y-axis will always
398 include zero, typically as the lowest value. This can be used to avoid
399 exaggerating the variance in the data.</td>
400 </tr>
401
402 <tr>
403 <td><b>rollPeriod</b></td>
404 <td><code>7</code></td>
405 <td>Number of days over which to average data. Discussed extensively above.</td>
406 </tr>
407
408 <tr>
409 <td><b>showRoller</b></td>
410 <td><code>true</code></td>
411 <td>Should the rolling average period text box be shown? Default is false.</td>
412 </tr>
413
414 <tr>
415 <td><b>colors</b></td>
416 <td><code>['red',&nbsp;'#00FF00']</code></td>
417 <td>List of colors for the data series. These can be of the form "#AABBCC"
418 or "rgb(255,100,200)" or "yellow", etc. If not specified, equally-spaced
419 points around a color wheel are used.</td>
420 </tr>
421
422 <tr>
423 <td><b>colorSaturation</b></td>
424 <td><code>1.0</code></td>
425 <td>If <b>colors</b> is not specified, saturation of the
426 automatically-generated data series colors. (0.0-1.0, default:
427 1.0)</td>
428 </tr>
429
430 <tr>
431 <td><b>colorValue</b></td>
432 <td><code>0.5</code></td>
433 <td>If colors is not specified, value of the data series colors, as in
434 hue/saturation/value. (0.0-1.0, default 0.5)</td>
435 </tr>
436
437 <tr>
438 <td><b>clickCallback</b></td>
439 <td><code>function(e,date){ alert(date); }</code></td>
440 <td>A function to call when a data point is clicked. The function should take
441 two arguments, the event object for the click and the date that was
442 clicked. (default null)</td>
443 </tr>
444
445 <tr>
446 <td><b>zoomCallback</b></td>
447 <td><code>function(minDate,maxDate) {}</code></td>
448 <td>A function to call when the zoom window is changed (either by zooming
449 in or out). minDate and maxDate are millis since epoch.</td>
450 </tr>
451
452 <tr>
453 <td><b>strokeWidth</b></td>
454 <td><code>2.0</code></td>
455 <td>Width of the data lines. This can be used to increase the contrast or
456 some graphs. (default 1.0)</td>
457 </tr>
458
459 <tr>
460 <td><b>dateWindow</b></td>
461 <td><code>[Date.parse('2006-01-01'),<br/>
462 (new&nbsp;Date()).valueOf()]</code></td>
463 <td>Initially zoom in on a section of the graph. Is of the form [earliest,
464 latest], where earliest/latest are millis since epoch. By default, the
465 full range of the input is shown.</td>
466 </tr>
467
468 <tr>
469 <td><b>valueRange</b></td>
470 <td><code>[10, 110]</code></td>
471 <td>Explicitly set the vertical range of the graph to [low, high]. By
472 default, some clever heuristics are used (see above).</td>
473 </tr>
474
475 <tr>
476 <td><b>labelsSeparateLines</b></td>
477 <td><code>true</code></td>
478 <td>Put &lt;br/&gt; between lines in the label string. Often used in
479 conjunction with <b>labelsDiv</b>. (default false)</td>
480 </tr>
481
482 <tr>
483 <td><b>labelsDiv</b></td>
484 <td><code>document.getElementById('foo')</code></td>
485 <td>Show data labels in an external div, rather than on the graph. (default
486 null)</td>
487 </tr>
488
489 <tr>
490 <td><b>labelsKMB</b></td>
491 <td><code>true</code></td>
492 <td>Show K/M/B for thousands/millions/billions on y-axis (default
493 false).</td>
494 </tr>
495
496 <tr>
497 <td><b>labelsDivWidth</b></td>
498 <td>250</td>
499 <td>Width (in pixels) of the div which shows information on the
500 currently-highlighted points.</td>
501 </tr>
502
503 <tr>
504 <td><b>labelsDivStyles</b></td>
505 <td>{}</td>
506 <td>Additional styles to apply to the currently-highlighted points div. For
507 example, { 'font-weigth': 'bold' } will make the labels bold.</td>
508 </tr>
509
510 <tr>
511 <td><b>highlightCircleSize</b></td>
512 <td><code>3</code></td>
513 <td>Size (in pixels) of the dot drawn over highlighted points (default 3).</td>
514 </tr>
515
516 <tr>
517 <td><b>drawPoints</b></td>
518 <td><code>false</code></td>
519 <td>Draw a small dot at each point, in addition to a line going through
520 the point. This makes the individual data points easier to see, but can
521 increase visual clutter in the chart. Default: false</td>
522 </tr>
523
524 <tr>
525 <td><b>pointSize</b></td>
526 <td><code>1.0</code></td>
527 <td>The size of the dot to draw on each point in pixels (see
528 drawPoints). A dot is always drawn when a point is "isolated", i.e.
529 there is a missing point on either side of it. This also controls the
530 size of those dots.</td>
531 </tr>
532
533 <tr>
534 <td><b>pixelsPerXLabel</b>, <b>pixelsPerYLabel</b></td>
535 <td>50</td>
536 <td>Number of pixels to require between each x- and y-label. Larger values
537 will yield a sparser axis with fewer ticks. Defaults: 60 (x-axis), 30
538 (y-axis).</td>
539 </tr>
540
541 <tr>
542 <td><b>xAxisLabelWidth</b>, <b>yAxisLabelWidth</b></td>
543 <td>50</td>
544 <td>Width (in pixels) of the x- and y-axis labels.</td>
545 </tr>
546
547 <tr>
548 <td><b>axisLabelFontSize</b></td>
549 <td>14</td>
550 <td>Size of the font (in pixels) to use in the axis labels, both x- and
551 y-axis.</td>
552 </tr>
553
554 <tr>
555 <td><b>rightGap</b></td>
556 <td>5</td>
557 <td>Number of pixels to leave blank at the right edge of the Dygraph. This
558 makes it easier to highlight the right-most data point.</td>
559 </tr>
560
561 <tr>
562 <td><b>errorBars</b></td>
563 <td><code>false</code></td>
564 <td>Does the data contain standard deviations? Setting this to true alters
565 the input format (see above). (default false)</td>
566 </tr>
567
568 <tr>
569 <td><b>sigma</b></td>
570 <td>2</td>
571 <td>When errorBars is set, shade this many standard deviations above/below
572 each point.</td>
573 </tr>
574
575 <tr>
576 <td><b>fractions</b></td>
577 <td>false</td>
578 <td>When set, attempt to parse each cell in the CSV file as "a/b", where a
579 and b are integers. The ratio will be plotted. This allows computation of
580 Wilson confidence intervals (see below).</td>
581 </tr>
582
583 <tr>
584 <td><b>wilsonInterval</b></td>
585 <td>true</td>
586 <td>Use in conjunction with the "fractions" option. Instead of plotting +/-
587 N standard deviations, dygraphs will compute a Wilson confidence interval
588 and plot that. This has more reasonable behavior for ratios close to 0 or
589 1.</td>
590 </tr>
591
592 <tr>
593 <td><b>customBars</b></td>
594 <td>false</td>
595 <td>When set, parse each CSV cell as "low;middle;high". Error bars will be
596 drawn for each point between low and high, with the series itself going
597 through middle.</td>
598 </tr>
599</table>
600
601<h2>Common Gotchas</h2>
602<p>Here are a few problems that I've frequently run into while using the
603dygraphs library.</p>
604
605<ul>
606 <li>Make sure your CSV files are readable! If your graph isn't showing up,
607 the XMLHttpRequest for the CSV file may be failing. You can determine whether
608 this is the case using tools like <a
609 href="http://www.getfirebug.com/">Firebug</a>.</li>
610
611 <li>Make sure your CSV files are in the correct format. They must be of the
612 form <code>YYYYMMDD,series1,series2,...</code>. And if you set the
613 <code>errorBars</code> property, make sure you alternate data series and
614 standard deviations.</li>
615
616 <li>dygraphs are not happy when placed inside a <code>&lt;center&gt;</code>
617 tag. This applies to the CSS <code>text-align</code> property as well. If you
618 want to center a Dygraph, put it inside a table with "align=center"
619 set.</li>
620
621 <li>Don't set the <code>dateWindow</code> property to a date. It expects
622 milliseconds since epoch, which can be obtained from a JavaScript Date
623 object's valueOf method.</li>
624
625 <li>Make sure you don't have any trailing commas in your call to the Dygraph
626 constructor or in the options parameter. Firefox, Chrome and Safari ignore
627 these but they can cause a graph to not display in Internet Explorer.</li>
628</ul>
629
630<a name="policy">
631<h2>Data Policy</h2>
632<p>dygraphs is purely client-side JavaScript. It does not send your data to any
633servers -- the data is processed entirely in the client's browser.</p>
634
635<p><font size=-1>Created May 9, 2008 by <a href=mailto:danvdk@gmail.com>Dan Vanderkam</a></font></p>
636
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