[alexk7]

This is not one of the weird things about Javascript. When you use a function (like map), always check the documentation to know its behaviour and don't assume it's similar to some similarly named function from another language. End of story.

[happytoexplain]

It's bewildering to me that one can look at the sheer volume of confusion generated by things like this and insist that it's not confusing.

[cbm-vic-20]

> don't assume it's similar to the same named function from every other language

[lucideer]

Not every language has such a function.

Even languages that do have different versions of it on different objects (e.g. Scala's zipWithIndex)