evaluating a object string

[jman]

var x = eval("{ 'flag' : 1 }");
alert(x);
alert(x.flag);

why doesn't the above work?

[Henry]

Re: evaluating a object string

On Mar 6, 12:17 pm, jman wrote:

            var x = eval("{ 'flag' : 1 }");
            alert(x);
            alert(x.flag);
>
why doesn't the above work?

Because the - eval - method treats its string input as a javascript
program and a javascript program commencing with an opening brace is a
program that starts with a block statement. That makes the content of
the block statement a syntax error.

If you want to have your string interpreted as an object literal you
have to force it into a context were it must be interpreted as an
expression. Putting parenthesis around it will achieve that end.

[SAM]

Re: evaluating a object string

Henry a écrit :

On Mar 6, 12:17 pm, jman wrote:

> var x = eval("{ 'flag' : 1 }");
> alert(x);
> alert(x.flag);
>>
>why doesn't the above work?

>
Because the - eval - method treats its string input as a javascript
program and a javascript program commencing with an opening brace is a
program that starts with a block statement. That makes the content of
the block statement a syntax error.
>
If you want to have your string interpreted as an object literal you
have to force it into a context were it must be interpreted as an
expression. Putting parenthesis around it will achieve that end.

can you give the code ?
I didn't understand where to put these parenthesis

[Henry]

Re: evaluating a object string

On Mar 6, 1:07 pm, SAM wrote:
<snip>

can you give the code ?
I didn't understand where to put these parenthesis

var x = eval("({ 'flag' : 1 })");

- or:-

var x = eval("("+"{ 'flag' : 1 }"+")");

[SAM]

Re: evaluating a object string

Henry a écrit :

On Mar 6, 1:07 pm, SAM wrote:
<snip>

>can you give the code ?
>I didn't understand where to put these parenthesis

>
var x = eval("({ 'flag' : 1 })");

Thought having tried that ... ? !

Thanks
now it rests to understand how that works :-)

Perhaps there is a way to see step to step how 'eval' treats the string.