javascript IE 不支持“insertBefore”
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IE doesn't support 'insertBefore'
提问by Teq1
I have a problem with this piece of code :
我对这段代码有问题：
var logo = document.getElementById("move_this");
prependElement('container', logo);
function prependElement(parentID, child) {
parent = document.getElementById(parentID);
parent.insertBefore(child, parent.childNodes[0]);
}
In IE I have an error:
在 IE 中我有一个错误：
SCRIPT438: Object doesn't support property or method 'insertBefore'
SCRIPT438：对象不支持属性或方法“insertBefore”
Is there a way to resolve this problem?
有没有办法解决这个问题？
回答by Dr.Molle
Use it like that:
像这样使用它：
var parent=document.getElementById(parentID);
otherwise parent will be global, but there always is a global parent-object, the parentwindow(and it is read-only).
否则 parent 将是全局的，但总是有一个全局父对象，即父窗口（并且它是只读的）。
Furthermore:IE requires as 2nd argument a valid node or null, so be sure that parent has childNodes to avoid errors:
此外：IE 需要一个有效节点或空作为第二个参数，因此请确保父节点具有 childNodes 以避免错误：
parent.insertBefore(child,(parent.hasChildNodes())
? parent.childNodes[0]
: null);
回答by DDM
insertBeforeworks correctly in IEas long as the 2nd parameter is a valid DOM element, or null( typeof nullis Objectand so is a typeofDOM element).
insertBefore在正常工作IE，只要该第二参数是有效DOM元素，或null（typeof null是Object，所以是一个typeofDOM元素）。
For an Array, any out of bound index (which in this case is 0as the children[]is empty) will return undefined. IE stops working in the following case as the 2nd param becomes undefined-
对于 an Array，任何越界索引（在本例中0为children[]空）都将返回undefined。IE 在以下情况下停止工作，因为第二个参数变为undefined-
parent.insertBefore(child, parent.childNodes[0])
//parent.childNodes[INDEX]
//where `INDEX` is greater than parent.childNodes.length
So, a better approach for this case will be
因此，对于这种情况，更好的方法是
var refEl = parent.childNodes[INDEX] || null;
parent.insertBefore(newRowHolderNode.childNodes[0], refEl);
回答by Dmitry Babich
As it was mentioned above, .insertBeforeworks only with valid node (explicit ID or global document reference). Local variable reference would fail:
如上所述，.insertBefore仅适用于有效节点（显式 ID 或全局文档引用）。局部变量引用会失败：
parent.insertBefore(child, localref); //error
In IE we can use .sourceIndexproperty to get current global index of "marker" element, before which new child is inserted. Here is the fix for IE:
在 IE 中，我们可以使用.sourceIndex属性来获取“标记”元素的当前全局索引，在该索引之前插入新的子元素。这是 IE 的修复：
parent.insertBefore(child, document.all[localref.sourceIndex]);
It is not necessary to use .sourceIndexproperty, if you know exactly where in parent tree you wish to insert an element. Following properties works just fine:
.sourceIndex如果您确切地知道要在父树中插入元素的位置，则没有必要使用属性。以下属性工作正常：
parent.insertBefore(child, parent.all[1]); //must be a child
parent.insertBefore(child, parent.children[2]); //any sane index
parent.insertBefore(child, parent.firstChild); //if at least one child exists
parent.insertBefore(child, parent.lastChild); //if at least one child exists
parent.insertBefore(child, localref.nextSibling]); //if not last child
parent.insertBefore(child, localref.previousSibling]); //if not first child
