[mbel]

Fat arrow is used to define a lambda function. The left-hand side of the arrow is argument list (_ is used to indicate lack of used arguments) and the right-hand side is the function body. It is equivalent to:

   var currentUrl = function () { return window.location.href; }

[thephyber]

> _ is used to indicate lack of used arguments

Note that this is a convention, not a requirement for the syntax (like in some other languages).

I've spent at least a few mins troubleshooting why `_.map` (from `lodash` npm module) didn't work inside of a fat function while fixing another developer's defect.

If you use `_` as a valid const/variable identifier anywhere in your codebase, I would recommend you ditch `_ => alert(1)` for something more obscure like `ø => alert(1)`

[TheDong]

It is not the same as that. the fat arrow doesn't change the value of "this" while the function definition does.

[geoelectric]

Given that "this" isn't referenced in the function, though, it's practically equivalent.

[simlevesque]

I think one is more efficient memory wise but I'm not sure which one.

[mmanfrin]

The non-fat-arrow one, as it does not need to carry around the context of `this` with it.

[hoosieree]

Do you have a reference for this? I always thought arrows were lighter weight because their `this` is static rather than dynamic.