我正在使用以下代码，但在 IE 中失败。消息是：
无法获取属性“添加”的值：对象为空或未定义”
我认为这只是 IE 支持问题。您将如何使以下代码在 IE 中工作？
有任何想法吗？
var img = new Image();
img.src = '/image/file.png';
img.title = 'this is a title';
img.classList.add("profilePic");
var div = document.createElement("div");
div.classList.add("picWindow");
div.appendChild(img);
content.appendChild(div);
classListIE9 及更低版本不支持该属性。不过 IE10+ 支持它。
使用className += " .."来代替。注意：不要省略空格：类名应添加在以空格分隔的列表中。
var img = new Image();
img.src = '/image/file.png';
img.title = 'this is a title';
img.className += " profilePic"; // Add profilePic class to the image
var div = document.createElement("div");
div.className += " picWindow"; // Add picWindow class to the div
div.appendChild(img);
content.appendChild(div);
正如其他人所提到的，classListIE9 及更早版本不支持。除了上面 Alex 的替代方案外，还有一些 polyfills 旨在成为替代品，即只需将这些包含在您的页面中，IE 就可以正常工作（著名的遗言！）。
https://github.com/eligrey/classList.js/blob/master/classList.js
在 IE 10 和 11 中，classList 属性定义在 HTMLElement.prototype 上。
为了让它在 SVG 元素上工作，应该在 Element.prototype 上定义该属性，就像在其他浏览器上一样。
一个非常小的修复是将确切的 propertyDescriptor 从 HTMLElement.prototype 复制到 Element.prototype：
if (!Object.getOwnPropertyDescriptor(Element.prototype,'classList')){
if (HTMLElement&&Object.getOwnPropertyDescriptor(HTMLElement.prototype,'classList')){
Object.defineProperty(Element.prototype,'classList',Object.getOwnPropertyDescriptor(HTMLElement.prototype,'classList'));
}
}
Element.prototype.classList = HTMLElement.prototype.classList会抛出Invalid calling object对于 IE 8 & 9，使用以下代码，我还为 Array.prototype.indexOf 包含了一个（缩小的）polyfill，因为 IE 8 本身不支持它（polyfill 来源：Array.prototype.indexOf
//Polyfill Array.prototype.indexOf
Array.prototype.indexOf||(Array.prototype.indexOf=function (value,startIndex){'use strict';if (this==null)throw new TypeError('array.prototype.indexOf called on null or undefined');var o=Object(this),l=o.length>>>0;if(l===0)return -1;var n=startIndex|0,k=Math.max(n>=0?n:l-Math.abs(n),0)-1;function sameOrNaN(a,b){return a===b||(typeof a==='number'&&typeof b==='number'&&isNaN(a)&&isNaN(b))}while(++k<l)if(k in o&&sameOrNaN(o[k],value))return k;return -1});
// adds classList support (as Array) to Element.prototype for IE8-9
Object.defineProperty(Element.prototype,'classList',{
get:function(){
var element=this,domTokenList=(element.getAttribute('class')||'').replace(/^\s+|\s$/g,'').split(/\s+/g);
if (domTokenList[0]==='') domTokenList.splice(0,1);
function setClass(){
if (domTokenList.length > 0) element.setAttribute('class', domTokenList.join(' ');
else element.removeAttribute('class');
}
domTokenList.toggle=function(className,force){
if (force!==undefined){
if (force) domTokenList.add(className);
else domTokenList.remove(className);
}
else {
if (domTokenList.indexOf(className)!==-1) domTokenList.splice(domTokenList.indexOf(className),1);
else domTokenList.push(className);
}
setClass();
};
domTokenList.add=function(){
var args=[].slice.call(arguments)
for (var i=0,l=args.length;i<l;i++){
if (domTokenList.indexOf(args[i])===-1) domTokenList.push(args[i])
};
setClass();
};
domTokenList.remove=function(){
var args=[].slice.call(arguments)
for (var i=0,l=args.length;i<l;i++){
if (domTokenList.indexOf(args[i])!==-1) domTokenList.splice(domTokenList.indexOf(args[i]),1);
};
setClass();
};
domTokenList.item=function(i){
return domTokenList[i];
};
domTokenList.contains=function(className){
return domTokenList.indexOf(className)!==-1;
};
domTokenList.replace=function(oldClass,newClass){
if (domTokenList.indexOf(oldClass)!==-1) domTokenList.splice(domTokenList.indexOf(oldClass),1,newClass);
setClass();
};
domTokenList.value = (element.getAttribute('class')||'');
return domTokenList;
}
});
/**
* Method that checks whether cls is present in element object.
* @param {Object} ele DOM element which needs to be checked
* @param {Object} cls Classname is tested
* @return {Boolean} True if cls is present, false otherwise.
*/
function hasClass(ele, cls) {
return ele.getAttribute('class').indexOf(cls) > -1;
}
/**
* Method that adds a class to given element.
* @param {Object} ele DOM element where class needs to be added
* @param {Object} cls Classname which is to be added
* @return {null} nothing is returned.
*/
function addClass(ele, cls) {
if (ele.classList) {
ele.classList.add(cls);
} else if (!hasClass(ele, cls)) {
ele.setAttribute('class', ele.getAttribute('class') + ' ' + cls);
}
}
/**
* Method that does a check to ensure that class is removed from element.
* @param {Object} ele DOM element where class needs to be removed
* @param {Object} cls Classname which is to be removed
* @return {null} Null nothing is returned.
*/
function removeClass(ele, cls) {
if (ele.classList) {
ele.classList.remove(cls);
} else if (hasClass(ele, cls)) {
ele.setAttribute('class', ele.getAttribute('class').replace(cls, ' '));
}
}
看一下这个
Object.defineProperty(Element.prototype, 'classList', {
get: function() {
var self = this, bValue = self.className.split(" ")
bValue.add = function (){
var b;
for(i in arguments){
b = true;
for (var j = 0; j<bValue.length;j++)
if (bValue[j] == arguments[i]){
b = false
break
}
if(b)
self.className += (self.className?" ":"")+arguments[i]
}
}
bValue.remove = function(){
self.className = ""
for(i in arguments)
for (var j = 0; j<bValue.length;j++)
if(bValue[j] != arguments[i])
self.className += (self.className?" " :"")+bValue[j]
}
bValue.toggle = function(x){
var b;
if(x){
self.className = ""
b = false;
for (var j = 0; j<bValue.length;j++)
if(bValue[j] != x){
self.className += (self.className?" " :"")+bValue[j]
b = false
} else b = true
if(!b)
self.className += (self.className?" ":"")+x
} else throw new TypeError("Failed to execute 'toggle': 1 argument required")
return !b;
}
return bValue;
},
enumerable: false
})
和 classList 将工作！
document.getElementsByTagName("div")[0].classList
["aclass"]
document.getElementsByTagName("div")[0].classList.add("myclass")
document.getElementsByTagName("div")[0].className
"aclass myclass"
就这样！