Code: var obj = { foo() {} }; obj.foo(10).bar Error message on Firefox: TypeError: obj.foo(...) is undefined Error message on Chrome: TypeError: Cannot read property 'bar' of undefined saying property name will make the error clearer.

not sure the best wording tho, something like: TypeError: obj.foo(...) is undefined and cannot read 'bar' property or: TypeError: Cannot read property 'bar' of obj.foo(...) that is undefined or something

I was the one confused on IRC (and the one arguably too dense to understand the error message for quite an embarrassing amount of time). Without opening Chrome and seeing its error I might've wasted even more time here. Background: My case was just _slightly_ different: foo=[1,2,3]; foo.find(x => x == 4).bar Having had a couple issues with old IEs just a couple days ago I consistently misparsed this as 'find' being missing/being undefined. I made sure that foo is an array, I saw that find is available in the debugger and yet evaluating this lead to the error message above, which .. again I read as _find_ being undefined. FWIW: I understand that you already _know_ that this is a function expression that returns undefined (because of the formatting of foo(...) in the error message). I guess it would've helped me a lot if this error would be tweaked from (taking my example) TypeError: foo.find(...) is undefined to TypeError: Result of foo.find(...) is undefined Including the property I tried to access might help as well, but this minor rephrasing would've solved my misunderstanding immediately. Sorry for the nitpicking/fussing over something this simple.