Referencing an object with a string

[Andy Dietler]

If I an objects called: MetaData1, MetaData2, MetaData3, etc. and I
want to use a loop to get the value of say each object's length how can
I do that?

for example:

for (i=1;i<=5;i++) {
alert(MetaData + i.length);
}

Obviously that isn't valid.

[Michael Winter]

On 02/08/2006 21:36, Andy Dietler wrote:

If I an objects called: MetaData1, MetaData2, MetaData3, etc. and I
want to use a loop to get the value of say each object's length how can
I do that?

Perhaps the simplest approach to have an array of MetaData. If that's
not possible for some reason, then the identifier may be constructed at
run-time and the object can be referenced as a property of some object.

For example, consider the following variables to be global:

var object1 = {},
object2 = {},
object3 = {};

As such, they are properties of the global object. This can be
referenced using the this operator (outside the scope of methods -
functions called as properties of an object - and constructor
functions), or the window object in browsers:

for (var i = 1; i <= 3; ++i) {

// Do something with: this["object" + i]

}

Mike

[Vic Sowers]

"Andy Dietler" <an*********@gmail.comwrote in message
news:11**********************@75g2000cwc.googlegro ups.com...

If I an objects called: MetaData1, MetaData2, MetaData3, etc. and I
want to use a loop to get the value of say each object's length how can
I do that?

for example:

for (i=1;i<=5;i++) {
alert(MetaData + i.length);
}

Obviously that isn't valid.

Use the evil 'eval' function:

alert(eval("MetaData"+i+".length"));

[Richard Cornford]

Vic Sowers wrote:
<snip>

Use the evil 'eval' function:

alert(eval("MetaData"+i+".length"));

One of the things that makes the - eval - function evil is that people
recommend its use where its use is not necessary and it becomes a means
by which people can do badly what could otherwise be done using normal
language constructs. That is, its use often stands as a barrier to
people learning javascript.

It is never necessary to use - eval - to reference a globally declared
variable as it is always possible to easily acquire a reference to the
global object, and then use a bracket notation property accessor to
reference its property.

<URL: http://jibbering.com/faq/#FAQ4_39 >

And good code design can eliminate any need to use - eval - to reference
object properties/variables at all.

<URL: http://jibbering.com/faq/#FAQ4_40 >

Richard.