Every style guide, and every linter, has a different notion about spacing. All of them use spaces of course but the actual indentation varies.
2 spaces is fairly standard and damn near the entire world uses it. There are other variations, like 4 spaces for multi-line var which closure-lint likes. To be honest, js style guides are mostly pointless when this many people are working on it. It's impossible to get everyone to use the same style and the tools that validate it aren't consistent between each other. But for the record, nobody except people who wish they were writing Python use 4 space indentation everywhere. It's the part of crockford's style guide that is most often ignored.
