what does eval function do in javascript language and what are its
usages?
6  2512 
On Mon, 13 Dec 2004 07:30:56 GMT, Dag Sunde <me@dagsunde.co m> wrote: <am******@hotma il.com> wrote in message
news:11******** **************@ z14g2000cwz.goo glegroups.com.. .
what does eval function do in javascript language and what are its
usages?
RTFM...
http://developer.netscape.com/librar...avascript.html
However, that manual doesn't exist any more. :P
<URL:http://docs.sun.com/source/816-6408-10/toplev.htm#1063 795>
Basically, it allows you to construct and run statements at run-time.
However, there are *very* few instances where you actually need to use
eval; there are usually much better ways of accomplishing the same thing.
Mike
--
Michael Winter
Replace ".invalid" with ".uk" to reply by e-mail.
<amoha...@hotma il.com> wrote: what does eval function do in javascript language and what are its
usages?
Here is an example usage. Let's say I have several drop-down menu and
certain buttons/events that require all items in the dropdown be
highlighted. Here is a thrown-together example of a highlight
function:
function selectAll(dd) {
eval('var box=document.fo rm.'+dd);
for (var i=0;i<box.optio ns.length;i++) { box.options[i].selected=true;
}
}
In this example, "eval('var box=document.fo rm.'+dd);" would evaluate to
"var box=document.fo rm.myDropDown". Now, if a user clicked a button
and I wanted it to highlight all the fields in the dropdown named
'myDropDown', you could use something like this:
<button onclick="select All('myDropDown ')" />Highlight Dropdown
#1</button>
This is especially useful for dynamically created controls that may
have dynamic names.
Daniel M. Hendricks http://www.danhendricks.com
On 13 Dec 2004 07:11:06 -0800, "Daniel M. Hendricks"
<dm*********@de spammed.com> wrote: <amoha...@hotm ail.com> wrote:
what does eval function do in javascript language and what are its
usages?
Here is an example usage.
This is especially useful for dynamically created controls that may
have dynamic names.
Maybe you should read the FAQ, before giving any more answers, just in
case the correct answer is there...
Jim.
JRS: In article <Qy************ *******@juliett .dax.net>, dated Mon, 13
Dec 2004 07:30:56, seen in news:comp.lang. javascript, Dag Sunde
<me@dagsunde.co m> posted : <am******@hotm ail.com> wrote in message
news:11******* *************** @z14g2000cwz.go oglegroups.com. .. what does eval function do in javascript language and what are its
usages? http://developer.netscape.com/librar...avascript.html
But also newsgroup FAQ sec 4.40.
--
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<URL:http://www.jibbering.c om/faq/> JL/RC: FAQ of news:comp.lang. javascript
<URL:http://www.merlyn.demo n.co.uk/js-index.htm> jscr maths, dates, sources.
<URL:http://www.merlyn.demo n.co.uk/> TP/BP/Delphi/jscr/&c, FAQ items, links.
>>what does eval function do in javascript language and what are its usages?
Here is an example usage. Let's say I have several drop-down menu and
certain buttons/events that require all items in the dropdown be
highlighted. Here is a thrown-together example of a highlight
function:
function selectAll(dd) {
eval('var box=document.fo rm.'+dd);
for (var i=0;i<box.optio ns.length;i++) { box.options[i].selected=true;
}
}
In this example, "eval('var box=document.fo rm.'+dd);" would evaluate to
"var box=document.fo rm.myDropDown".
The only advantage to using eval in this way is that it might allow a
very slow-witted scripter to avoid learning about the subscript notation.
function selectAll(dd) {
var box = document.form[dd];
It is almost always wrong to use the eval function. http://www.crockford.com/javascript/survey.html This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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