Object literal syntax

shortt · May 24th, 2005, 02:13 PM

I am familiar with this type of literal object syntax:

Code:

var myObject = {"bindings": [
        {"ircEvent": "PRIVMSG", "method": "newURI", "regex": "^http://.*"},
        {"ircEvent": "PRIVMSG", "method": "deleteURI", "regex": "^delete.*"},
        {"ircEvent": "PRIVMSG", "method": "randomURI", "regex": "^random.*"}
    ]
};

as well as this, for arrays:

Code:

slides = [
    {url: 'slide0001.html', title: 'Looking Ahead'},
    {url: 'slide0008.html', title: 'Forecast'},
    {url: 'slide0021.html', title: 'Summary'}
];

but the following is new to me:

Code:

obj[âonâ + event]

What does this mean? obj is an object, I think.

Thanks,
Tim

shortt · May 25th, 2005, 12:14 PM

Update:

So I've figured out that obj["on" + event] is an object, and that it's object property syntax (e.g. obj["property"]).

What is still confusing me is the + event part. Does the "on" + event just resolve to a string (given that event would be a reference to another object)?

nzakas · May 27th, 2005, 03:07 PM

Yes, it does resolve to a string because anything plus a string equals a string. Of course, what that final value is will depend on the value of the event variable.

Nicholas C. Zakas
Author, Professional JavaScript for Web Developers (ISBN 0764579088)
http://www.nczonline.net/

joefawcett · May 28th, 2005, 11:47 AM

To clarify:

Code:

obj[âonâ + event]

if event = "click" then
the above equals:

Code:

obj["onclick"]

which is the same as:

Code:

obj.onclick

Presumably the author was tring to dynamically assign event handlers.

--

Joe (Microsoft MVP - XML)

shortt · May 28th, 2005, 07:44 PM

@ Joe & Nicholas: Thanks.

@ Joe: yes, I can see now that that's exactly what the author was doing.