我最近遇到了一个相当严重的错误，其中代码通过JavaScript动态加载<select>。这个动态加载的<select>有一个预先选定的值。在IE6中，我们已经有代码来修复选中的<option>，因为有时<select>的selectedIndex值会与选中的<option>的index属性不同步，如下所示:
field.selectedIndex = element.index;
然而，这段代码没有工作。即使字段的selectedIndex设置正确，最终还是会选择错误的索引。但是，如果我在正确的时间插入alert()语句，则会选择正确的选项。考虑到这可能是某种时间问题，我尝试了一些以前在代码中见过的随机方法:
var wrapFn = (function() {
var myField = field;
var myElement = element;
return function() {
myField.selectedIndex = myElement.index;
}
})();
setTimeout(wrapFn, 0);
这招奏效了!
我找到了解决问题的方法，但我不知道为什么这能解决我的问题，这让我感到不安。有人有官方解释吗?什么浏览器问题，我避免调用我的函数“稍后”使用setTimeout()?
//When need "new a", setTimeout(fn, 0) is useful, when need to wait some action. Example:
var a = function (){console.log('a');};
var b = function(){setTimeout(b, 100);}; //wait some action before override this function
//without setTimeout:
console.log('no setTimeout: b.toString():', b.toString());
b(); //"b" is an old function
console.log('no setTieout: a.toString(): ', a.toString());
a(); //and "a" is not overrided
setTimeout(//but with setTimeout(fn, 0):
function(){
console.log('After timeout 0, b.toString(): ', b.toString());
b(); //"b" is a new function
console.log('After timeout 0, a.toString(): ', a.toString());
a(); //and "a" is overrided
},
0
);
//override var "b", which was been undefined
b = function (){
a = function(){console.log('new a');};
}
