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JSXCompressor - Delivering compressed JavaScript
The open source library JSXGraph (http://jsxgraph.org) contains utilities to read files which
have been compressed by the ZLIB (http://zlib.org) library. That means, JSXGraph has a pure
JavaScript implementation of DEFLATE, unzip and base64_decode.
This can be used for delivering compressed JavaScript inside of an HTML file.
Of course, with todays browsers it depends on the transmission bandwidth if this is worthwile.
If the web server does not support compression of data, then this tool may be an option.
One possibility to compress the JavaScript source is to use PHP. The code below
writes the content of a JavaScript file as a compressed, base64 encoded string
into the HTML. This string can be accessed via the JavaScript variable jsxcompressed.
<!-- -------------------------------------------------------- -->
<?php
function jxgcompress($filename)
{
if (file_exists($filename)) {
$base64 = base64_encode(gzcompress(rawurlencode(file_get_contents($filename)),9));
echo "var jxgcompressed = \"$base64\";\n";
} else {
throw new Exception("$filename not found");
}
}
?>
<script type="text/javascript">
<?php
jxgcompress("./helloworld.js");
?>
</script>
<!-- -------------------------------------------------------- -->
To uncompress and run this code, the following code has to be included:
<!-- -------------------------------------------------------- -->
<script src="./jsxcompressor.js" type="text/javascript"></script>
<script type="text/javascript">
eval(JXG.decompress(jxgcompressed));
</script>
<!-- -------------------------------------------------------- -->
Thats all.
The zip file jsxcompressor.zip contains two examples: testhelloworld.php and testjsxgraph.php
Enjoy,
Alfred Wassermann
(alfred.wassermann@uni-bayreuth.de)
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