What's more important in JS: performance, or the understandability of the code?

[Jeff_Mott]

@markbrown4

can lead to errors(hoisting)

Personally, I use a linter to catch hoisting mistakes.

@markbrown4

it is less flexible(can’t reassign)

I don’t understand why everyone in this thread has been saying that. Function declarations are absolutely reassignable.

function f() {
    console.log('f');
}
f = function() {
    console.log('f2');
}
f(); // f2

That being said, for the sake of our code being understandable, we shouldn’t reassign functions, regardless if it’s a function expression or declaration.

@felgall

Anyway, my version can be easily extended to include removeEvent as follows:
var removeEvent;
var addEvent = function(ob, type, fn) {

What if someone tries to call removeEvent before addEvent?