JavaScript version in XPI

[Daniel Fournier]

What is the JavaScript version in use when XPI install.js is running?

I get unespectable JavaScript behaviour making me think that JS version 
is not 1.5 (in Mozilla 1.4).

For instance:

var astring = 'STRING%sTEST%sONE';
var amatch = astring.match(/%s/g);
var aspit = astring.split(/%s/);
This code is generating an error report in install.log:

     ** Line: 0 can't convert Error to string
     ** Line: 88        undefined is not a constructor
Daniel