var myFunction = function functionName()

Question

I always used to write functions like this:

var myFunction = function(param) {
    console.log(param);
};
myFunction('myFunction');

Now I've seen this:

var otherFunction = function whyNameHere(param) {
    console.log(param);
};
otherFunction('otherFunction');

and I'm wondering what is whyNameHere? When and why should functions be written like this? Also I can call it exactly the same as the myFunction function above.. why should someone write whyNameHere? Also is there a naming for this kind of function?

If anyone wants to play with it, here is a fiddle

Why do either? You can use ```function otherFunction(param){console.log(param)};``` — JasTonAChair, Oct 19 '15 at 11:10
It's for call stacks and setting `.name` property, but the question is a dupe. — Bartek Banachewicz, Oct 19 '15 at 11:11
@BartekBanachewicz, your variant not same as ask OP, i sure was a more relevant — Grundy, Oct 19 '15 at 11:12
@BartekBanachewicz remove the duplicate because it's not the same question. See what OP ask — Marcos Pérez Gude, Oct 19 '15 at 11:12
@MarcosPérezGude It's not the same question, but the same answer applies, really. — Bartek Banachewicz, Oct 19 '15 at 11:12
I don't see anything related with `var myfunc = function anotherName()` in the answer of the duplicate you've post — Marcos Pérez Gude, Oct 19 '15 at 11:13
@JasTonAChair it's just a simple example. But most of the times I need a function to return something so I don't know. just how I'm used to do it and to assign a function as a variable — caramba, Oct 19 '15 at 11:14
@MarcosPérezGude If you can add 2 to 2, you can figure out what's going on and how this affects the value created. — Bartek Banachewicz, Oct 19 '15 at 11:14
OK, I didn't know they were different. Thanks for raising that @caramba — JasTonAChair, Oct 19 '15 at 11:14
@caramba, in nutshell, when in second case you can do: `var otherFunction = function whyNameHere(param) { if(condition) whyNameHere(newparam); };` in first: not — Grundy, Oct 19 '15 at 11:15
@Grundy how is that different to `var otherFunction = function whyNameHere(param) { if(condition) otherFunction(newparam); };`? — Reinstate Monica Cellio, Oct 19 '15 at 11:17
@Archer, you can assign another value to `otherFunction` before call it — Grundy, Oct 19 '15 at 11:18
In my opinion, it's not a duplicate and the syntax has no sense. This: `var otherFunction = function whyNameHere(param) { whyNameHere("Oh");};` causes an infinite loop, and call `whyNameHere` outside doesn't works, so there is no sense for this — Marcos Pérez Gude, Oct 19 '15 at 11:18

Bartek Banachewicz · Accepted Answer · 2015-10-19T11:36:08.500

0

Using that allows you to set the .name property on the created function object.

> var f = function g() { }
< undefined
> f.name
< "g"

It's impossible to change it later:

> f.name = "f"
< "f"
> f.name
< "g"

And it's useful for... things.

Example:

setImmediate(function unicorns() {
    console.log("rainbow");
    throw "glitter";
});

Will present itself on the stack trace as:

Uncaught glitter
    unicorns @ VM691:4

Instead of

Uncaught glitter
    (anonymous function) @ VM693:4

edited Oct 19 '15 at 11:36

answered Oct 19 '15 at 11:18

Bartek Banachewicz

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[Function.name](https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Function/name) This is a new technology, part of the ECMAScript 2015 (ES6) standard. So available not in all browser – Grundy Oct 19 '15 at 11:22
@Grundy maybe it's just me, but for me ES7 is new technology. ES6 has been here for a while, really. Sure, not fully locked and standarized, but you get the point. – Bartek Banachewicz Oct 19 '15 at 11:22
seems to full support ES6 a lot of time – Grundy Oct 19 '15 at 11:23
hmm, well now from what I understood the answers (which my question should be the duplicate of) I could/can use g() only inside f !? so if that is true that would of actually have been the answer on my question (as part one) the seccond part was if that has a name ... – caramba Oct 19 '15 at 11:23
1

@caramba The `g` name doesn't leak outside the assignment, if that's what you're asking about. – Bartek Banachewicz Oct 19 '15 at 11:24
well yes thats kind of what I was asking. I didn't see any reason of how and where to use it.. – caramba Oct 19 '15 at 11:25
If you can explain `And it's useful for... things.` with a working example of sense I'll like your answer. I like the joke a lot but it really doesn't helps.. – caramba Oct 19 '15 at 11:30
@caramba sure. There you go. – Bartek Banachewicz Oct 19 '15 at 11:36

var myFunction = function functionName()

1 Answers1