Hi T.J.
I'm very grateful for this straight forward and easy to follow
explanation - it's certainly broadened my whole understanding of
JavaScript arrays and object literals - and helped me write a concise
solution to the JavaScript problem I was facing.
All the best
George
On Dec 5, 1:37 pm, "T.J. Crowder" <[EMAIL PROTECTED]> wrote:
> Hi George,
>
> (It's a JavaScript rather than Prototype/script.aculo.us question,
> yes.)
>
> This object literal / JSON data:
>
> [{bookingref:'A6D98FGR', canceled:0}]
>
> ...defines an array with a single element, which is an object instance
> with two properties: bookingref (value 'A6D98FGR') and canceled
> (value 0).
>
> You can get the values just by referring to the properties of the
> object, so:
>
> var x = RS[0].bookingref;
> alert(x); // Alerts 'A6D98FGR'
>
> JavaScript allows you to use property names both literally with dot
> notation (as above), and _also_ via string names using bracket
> notation; we could write the above like this instead:
>
> var x = RS[0]['bookingref'];
> alert(x); // Alerts 'A6D98FGR'
>
> Note the quotes, the square brackets, and the absense of the dot.
>
> If you don't know the names of the properties in advance, you can use
> the for..in loop to iterate over the names of the object's properties:
>
> var name;
> for (name in RS[0]) {
> alert(name + '=' + RS[0][name]);
>
> }
>
> In the loop, the variable 'name' is set on each iteration to the name
> of a property on the object, as a string. This is powerful when
> combined with bracket notation. On the object defined in your JSON
> above, that will show "bookingref=A6D98FGR" and "canceled=0"; the
> order is not defined and almost certainly will vary from
> implementation to implementation.
>
> Note that for..in is for iterating over the properties of an object,
> *not* the elements of an array. Many JavaScript programmers think
> it's for the latter, and they get into trouble as a result because
> Prototype adds some properties to arrays that they're not expecting to
> see.
> Details:http://proto-scripty.wikidot.com/prototype:tip-looping-through-arrays
>
> But again, it's totally fine for looping through the properties on an
> object, like your RS[0].
>
> HTH,
> --
> T.J. Crowder
> tj / crowder software / com
>
> On Dec 5, 12:18 pm, George <[EMAIL PROTECTED]> wrote:
>
> > Hi Folks,
>
> > This may be more of a pure JavaScript question than Prototype, but
> > here goes:
>
> > If I have a JSON array called RS for example containing this:
> > [{bookingref:'A6D98FGR', canceled:0}]
> > is there a way for me to programatically get the names and values?
>
> > I'd like to be able to do something like
> > RS[0].[0].name ((would be 'bookingref'))
> > RS[0].[0].value ((would be 'A6D98FGR'))
>
> > I hope that makes sense.
>
> > Many thanks
>
> > George
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