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[DWR]Max depth exceeded when dereferencing

使用DWR做一個demo的時候，總是報出 JS Alert: Max depth exceeded when dereferencing ...

function ?update()? {

? // var?name?=?dwr.util.getValue("demoName");

? var ?name? = ?document.getElementById( " demoName " );

???UpdateText.sayHello(name,?callback);

}

function ?callback(data)

{

? var ?d? = ?data? + ? " ?

" ;

?dwr.util.setValue( " demoReply " ,?d);

}

用上面那一句 var?name?=?dwr.util.getValue("demoName"); 的時候就不會報出這個錯誤
看了一下util.js的源碼，發現其實它返回的是??document.getElementById("xxx").value ，所以我們這里修改為
var?name?=?document.getElementById("demoName").value;?這就和 dwr.util.getValue("demoName") 等價了

util.js 關于getValue函數的源碼?

/* *

?*?Read?the?current?value?for?a?given?HTML?element.

?*?@see?http://getahead.org/dwr/browser/util/getvalue

? */

dwr.util.getValue? = ? function (ele,?options)? {

?? if ?(options? == ? null )?options? = ? {} ;

?? var ?orig? = ?ele;

?? if ?( typeof ?ele? == ? " string " )? {

????ele? = ?dwr.util.byId(ele);

???? // ?We?can?work?with?names?and?need?to?sometimes?for?radio?buttons,?and?IE?has

???? // ?an?annoying?bug?where?getElementById()?returns?an?element?based?on?name?if

???? // ?it?doesn't?find?it?by?id.?Here?we?don't?want?to?do?that,?so:

???? if ?(ele? && ?ele.id? != ?orig)?ele? = ? null ;

??}

?? var ?nodes? = ? null ;

?? if ?(ele? == ? null )? {

???? // ?Now?it?is?time?to?look?by?name

????nodes? = ?document.getElementsByName(orig);

???? if ?(nodes.length? >= ? 1 )?ele? = ?nodes.item( 0 );

??}

?? if ?(ele? == ? null )? {

????dwr.util._debug( " getValue()?can't?find?an?element?with?id/name:? " ? + ?orig? + ? " . " );

???? return ? "" ;

??}

?? if ?(dwr.util._isHTMLElement(ele,? " select " ))? {

???? // ?Using?"type"?property?instead?of?"multiple"?as?"type"?is?an?official?

???? // ?client-side?property?since?JS?1.1

???? if ?(ele.type? == ? " select-multiple " )? {

?????? var ?reply? = ? new ?Array();

?????? for ?( var ?i? = ? 0 ;?i? < ?ele.options.length;?i ++ )? {

???????? var ?item? = ?ele.options[i];

???????? if ?(item.selected)? {

?????????? var ?valueAttr? = ?item.getAttributeNode( " value " );

?????????? if ?(valueAttr? && ?valueAttr.specified)? {

????????????reply.push(item.value);

??????????}

?????????? else ? {

????????????reply.push(item.text);

??????????}

????????}

??????}

?????? return ?reply;

????}

???? else ? {

?????? var ?sel? = ?ele.selectedIndex;

?????? if ?(sel? != ? - 1 )? {

???????? var ?item? = ?ele.options[sel];

???????? var ?valueAttr? = ?item.getAttributeNode( " value " );

???????? if ?(valueAttr? && ?valueAttr.specified)? {

?????????? return ?item.value;

????????}

???????? return ?item.text;

??????}

?????? else ? {

???????? return ? "" ;

??????}

????}

??}

?? if ?(dwr.util._isHTMLElement(ele,? " input " ))? {

???? if ?(ele.type? == ? " radio " )? {

?????? if ?(nodes? && ?nodes.length? >= ? 1 )? {

???????? for ?( var ?i? = ? 0 ;?i? < ?nodes.length;?i ++ )? {

?????????? var ?node? = ?nodes.item(i);

?????????? if ?(node.type? == ?ele.type)? {

???????????? if ?(node.checked)? return ?node.value;

??????????}

????????}

??????}

?????? return ?ele.checked;

????}

???? if ?(ele.type? == ? " checkbox " )? {

?????? if ?(nodes? && ?nodes.length? >= ? 1 )? {

???????? var ?reply? = ?[];

???????? for ?( var ?i? = ? 0 ;?i? < ?nodes.length;?i ++ )? {

?????????? var ?node? = ?nodes.item(i);

?????????? if ?(node.type? == ?ele.type)? {

???????????? if ?(node.checked)?reply.push(node.value);

??????????}

????????}

???????? return ?reply;

??????}

?????? return ?ele.checked;

????}

???? return ?ele.value;

??}

?? if ?(dwr.util._isHTMLElement(ele,? " textarea " ))? {

???? return ?ele.value;

??}

?? if ?(dwr.util._shouldEscapeHtml(options))? {

???? if ?(ele.textContent)? return ?ele.textContent;

???? else ? if ?(ele.innerText)? return ?ele.innerText;

??}

?? return ?ele.innerHTML;

} ;

posted on 2007-08-12 17:54 jht 閱讀(4220) 評論(5) 編輯收藏所屬分類: J2EE 、DWR

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