[thelist] good ECMAScript (or JavaScript) guide/reference

Can anyone recommend a good ECMAScript guide and reference? I figure I
should try to find one, since this is the recommended scripting language,
as opposed to JavaScript. But a good JavaScript guide and reference would
be good, too. (I am looking for something which would be good for someone
who already knows the basics of JavaScript.) Any thoughts on how useful
ECMAScript actually is at this point would also be welcome. TIA!

Sarah