Question

I’m writing a JavaScript parser based on ECMA-262. I’d be interested to know how much I’d need to change to make it ECMA-357 compatible.

Are there any syntactic differences?

Answer 1

There is a number of syntax extensions. The most important one are the XML literals (see section 11.1.4 and 11.1.5):

var foo = <xml>
  foo
</xml>;
var bar = <>
  <tag attr={(1+2).toFixed(2)}/>
  {foo}
</>;

The example above shows the special case of an empty root tag and JavaScript expressions in XML code.

You also have some expressions that aren’t valid in ECMA-262 (see section 11.2):

xml.@attr           // get attribute attr
xml.*               // get all child elements
xml.@*              // get all attributes
xml..foo            // get all <foo> tags
xml..foo.(@id == 1) // filter <foo> tags by id attribute

There are namespaces (see section 11.1.2):

xml.soap::foo       // get <foo> child tags with namespace soap
xml.@soap::attr     // get attribute with namespace soap

There is the default XML namespace statement which is syntactically a very unusual construct (see section 12.1):

default xml namespace = new Namespace("http://foo/bar");

Finally, there is the for each .. in loop which is similar to for .. in (see section 12.3):

for each (var foo in xml)
{

}

As far as I know these are all the syntax differences – but you’ve probably got more than enough already.