Why does Eclipse mark valid JavaScript with an error?

Question

The JavaScript:

[a,b] = [b,a];

The Eclipse error:

The left-hand side of an assignment must be a variable

Is there some plugin or something I need in order to get Eclipse to correctly inspect JavaScript?

Answer 1

It's only valid in Mozilla's JavaScript implementation, found in Firefox for example.

Technically this is actual "JavaScript" according to a more technical definition of the word, but it's currently not valid "ECMAScript", which is usually what people are talking about when they use the word "JavaScript".