What does a + function() { } notation do?

Question

I am reading a javascript file written by someone that has a couple of functions for modifying CSS and other things and I am not a pro level at Javascipt; I am seeing a piece of code like

    + function(a) {
    "use strict";

    function b() {
        var a = document.createElement("bootstrap"),
            b = {
                WebkitTransition: "webkitTransitionEnd",
                MozTransition: "transitionend",
                OTransition: "oTransitionEnd otransitionend",
                transition: "transitionend"
            };
        for (var c in b)
            if (void 0 !== a.style[c]) return {
                end: b[c]
            }
    }
    a.fn.emulateTransitionEnd = function(b) {
        var c = !1,
            d = this;
        a(this).one(a.support.transition.end, function() {
            c = !0
        });
        var e = function() {
            c || a(d).trigger(a.support.transition.end)
        };
        return setTimeout(e, b), this
    }, a(function() {
        a.support.transition = b()
    })
}(window.jQuery), + function(a) {

What does adding the + sign do to a javascript function ? The code is really long so I just pasted whatever i thought was relevant.

I have found my answer and this is a duplicate post of another but for those who want the full source code it is here source code

If these functions are returning some integers, maybe it's adding all values of functions? — Justinas, Aug 20 '14 at 11:36
This does not seem like enough information as it ends in the middle of the script. — Johnston, Aug 20 '14 at 11:37
It's a unary operator. [It could as well be any other unary operator](http://stackoverflow.com/a/7587056/1048572). — Bergi, Aug 20 '14 at 11:37
It does an arithmetic operation which is resulting in NaN. The complete source would be helpful. A '+' is often used before function _calls_ to cast the return value to number. Example: `+ new Date()` — Julian Hollmann, Aug 20 '14 at 11:39
@DimitarDimitrov: That is what certain minifiers do to reduce code size. In face, this whole script looks like a pretty-printed minified script, given all the one-letter variable names. — Bergi, Aug 20 '14 at 11:40
for those of you who are looking for the source code, here it is http://randbresearch.co.uk/assets/js/scripts.min.js?ver=2a3e700c4c6e3d70a95b00241a845695 — Bazinga777, Aug 20 '14 at 11:41
@DimitarDimitrov It's propably minified code that got prettified. — Julian Hollmann, Aug 20 '14 at 11:41
@Bergi Oh, I see, yeah I should've assumed :) You must be right. — Dimitar Dimitrov, Aug 20 '14 at 11:42

score 2 · Accepted Answer · edited May 23 '17 at 11:49

2

looking at this other question (JavaScript plus sign in front of function name) on the same subject, the following seems to be the answer:

It forces the parser to treat the part following the + as an expression. This is usually used for functions that are invoked immediately

source - https://stackoverflow.com/a/13341710/970847

edited May 23 '17 at 11:49

Community

1
1

answered Aug 20 '14 at 11:37

Dave Haigh

3,919
5
30
56

Thanks, I'll can read up on this now. I googled for answers but couldnt find an answer. So it is an IIFE; thats all. – Bazinga777 Aug 20 '14 at 11:39
1

Please [vote to close](https://stackoverflow.com/help/privileges/close-questions) the question as a duplicate (or flag it for mod attention), instead of posting the link as an answer. – Bergi Aug 20 '14 at 11:41

score 0 · Answer 2 · edited May 23 '17 at 12:13

0

It forces the parser to treat the part following the + as an expression. This is usually used for functions that are invoked immediately.

From here JavaScript plus sign in front of function name

edited May 23 '17 at 12:13

Community

1
1

answered Aug 20 '14 at 11:37

Joanvo

5,200
2
21
34

Please [vote to close](https://stackoverflow.com/help/privileges/close-questions) the question as a duplicate (or flag it for mod attention), instead of posting the link as an answer. – Bergi Aug 20 '14 at 11:43

What does a + function() { } notation do?

2 Answers2