Re: Web Storage how to check for support?
2009/8/5 Darin Adler da...@apple.com:
On Aug 5, 2009, at 9:42 PM, Jonas Sicking wrote:
2009/8/1 João Eiras jo...@opera.com:
How can one in a script check for UA support?
else if(localStorage){}
does not work for Opera**.
This obviously does not work because you need to prefix localStorage with
window if(window.localStorage) else the script breaks because localStorage
is a undefined identifier while window.localStorage looks up a property in
the window. Different things, specific to ecmascript itself.
No, the window object is the global object where all global variables are
defined. Try the following:
script
a = 10;
alert(window.a);
/script
There is no variable declaration there.
I think the point is that if there is no global variable of name x, then
window.x yields undefined, whereas x yields an exception.
That means that one way to check for the localStorage object is:
if (window.localStorage) {
// Code using localStorage here.
}
If you instead do:
if (localStorage) {
// Code using localStorage here.
}
Then you end up with code that simply throws an exception in browsers that
don’t have localStorage.
Correct.
The 'typeof' operator would be another good option here.
Type converting and even getting host object properties has been the
source of errors in IE.
For example:-
javascript: var op = document.createElement(div).offsetParent;
- errs in IE.
The typeof operator can be used to avoid such errors.
if(typeof window.localStorage != undefined){
// property is not undefined.
}
Considerations of usage context are important and relevant. Good question.
-- Darin
Regards,
Garrett
Re: Web Storage how to check for support?
On Aug 5, 2009, at 9:42 PM, Jonas Sicking wrote:
2009/8/1 João Eiras jo...@opera.com:
How can one in a script check for UA support?
else if(localStorage){}
does not work for Opera**.
This obviously does not work because you need to prefix
localStorage with window if(window.localStorage) else the script
breaks because localStorage is a undefined identifier while
window.localStorage looks up a property in the window. Different
things, specific to ecmascript itself.
No, the window object is the global object where all global
variables are defined. Try the following:
script
a = 10;
alert(window.a);
/script
I think the point is that if there is no global variable of name x,
then window.x yields undefined, whereas x yields an exception.
That means that one way to check for the localStorage object is:
if (window.localStorage) {
// Code using localStorage here.
}
If you instead do:
if (localStorage) {
// Code using localStorage here.
}
Then you end up with code that simply throws an exception in browsers
that don’t have localStorage.
-- Darin
Re: Web Storage how to check for support?
2009/8/1 João Eiras jo...@opera.com:
How can one in a script check for UA support?
else if(localStorage){}
does not work for Opera**.
Hi.
This obviously does not work because you need to prefix localStorage with
window if(window.localStorage) else the script breaks because localStorage
is a undefined identifier while window.localStorage looks up a property in
the window. Different things, specific to ecmascript itself.
No, the window object is the global object where all global variables
are defined. Try the following:
script
a = 10;
alert(window.a);
/script
/ Jonas
Re: Web Storage how to check for support?
How can one in a script check for UA support?
else if(localStorage){}
does not work for Opera**.
Hi.
This obviously does not work because you need to prefix localStorage with window
if(window.localStorage) else the script breaks because localStorage is a
undefined identifier while window.localStorage looks up a property in the window.
Different things, specific to ecmascript itself.
Re: Web Storage how to check for support?
http://dev.w3.org/html5/webstorage/#the-storage-interface
Web Storage how to check for support?
How can one in a script check for UA support?
How about either of the following, they both worked as expected for me.
// Check for the Storage interface
if (window.Storage) { ... }
// Check for an instance of the interface
if (window.localStorage) { ... }
- Joe
Re: Web Storage how to check for support?
Joseph,
thanks for that,
had tried document but not window
regards
~:
On 27 Jul 2009, at 16:41, Joseph Pecoraro wrote:
http://dev.w3.org/html5/webstorage/#the-storage-interface
Web Storage how to check for support?
How can one in a script check for UA support?
How about either of the following, they both worked as expected for
me.
// Check for the Storage interface
if (window.Storage) { ... }
// Check for an instance of the interface
if (window.localStorage) { ... }
- Joe
