Uses of colon in javascript

Question

1. Assign object literal properties var foo = { bar : 'hello'};
2. Ternary var cats = happy ? "yes" : "no";
3. Label a statement outer_loop: for(i=0; i<3; i++)
4. What else?

I'm poking through a sharepoint 2010 file and I keep running into this syntax

someFunction: ;

For instance, there is a file where the following function is declared near the top:

function ULSqvN() {
    var o = new Object;
    o.ULSTeamName = "SharePoint Portal Server";
    o.ULSFileName = "SocialData.js";
    return o;
}

and then later in the file we find the following

PageUrlNormalizer = function () {
    ULSqvN: ; //<---------------- This guy here --------------------------
    try {
        this._url = _normalizedPageUrlForSocialItem
    } catch (a) {
        this._url = ""
    }
};

What is this doing?

jsFiddle with full file. This same ULSqvN: ; occurs 47 times in the file.

edit: Added full code.

PS: Consensus seems to be that the sharepoint use of colon is "not actual javascript, possibly used as a marker for some external purpose". The browser sees it as a vestigial label and so causes no errors. Thanks for all the replies, I have left the actual uses at the top so that the question contains the appropriate answers. question about same code

Answer 1

It has no purpose javascript-wise (since in javascript you would only label something that you can continue or break), it might be used as a some kind of comment or marker for some parsing script. At worst it's just dead code with no purpose whatsoever.

Edit: looks like sharepoint uses it for some diagnostic information: What does this Javascript code do?

Answer 2

These are labels. Usually they are used to break out of several nested loops at once.

Example

function foo ()
{
    dance:
    for(var k = 0; k < 4; k++){
        for(var m = 0; m < 4; m++){
            if(m == 2){
                break dance;
            }
        }
    }
}

Credit: this answer.