7.1 says function expressions are always unnamed, but this changed in ES6

7.1 contains this statement:

Function declarations are named, so they’re easier to identify in call stacks.

Anonymous function expressions assigned to a binding are also named, per ES6 semantics (1.e.iii). That is, the “bad” example const foo = function () { }; is the same as const foo = function foo() { };, which is equivalent to the “good” example function foo() { } in that respect.

Should the statement be qualified that it’s only a distinction for ES5 and below ?

[ljharb]

@amberleyromo indeed, they should be distinct. This is to improve readability and greppability - it lets you use a short variable name, but a long, verbose, unique function name; also, when self-referencing the function, it makes it very clear that you’re referring to the lexical name binding, not the containing variable.

[ljharb]

@tandav In your last example, the first function doesn’t have a .name - which means in debugging, it’s likely to show up as an anonymous function. In the latter example, it will show up with the name sum - and when you grep for it, all the uses in the file will use my_sum, so the actual function will be easier to locate.