[Pas2js] JSValue Helpers

[helioroots roots]

example
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freepascal.org/pipermail/pas2js/attachments/20190918/000b2209/attachment.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: sample.zip
Type: application/zip
Size: 2476 bytes
Desc: not available
URL: <http://lists.freepascal.org/pipermail/pas2js/attachments/20190918/000b2209/attachment.zip>