If the element you are referring to does not already include a Javascript object property for a given attribute (as others have described), then setting that property will not propagate the change back to the DOM, it just adds the named property to the Javascript object, and the DOM ignores it. For example, getting the element mySpan by id and then doing mySpan.class = 'warning' will do nothing, whether or not the span element in question already has a class attribute defined, because mySpan.class is not defined in the Javascript object for a span element. You have to use mySpan.setAttribute('class', 'warning').

然而，第二个细微差别是使用mySpan设置Javascript对象的innerHTML属性。setAttribute("innerHTML"， someHTML)不会更新元素的内容。我不知道Javascript是如何捕获mySpan的。innerHTML = something，并调用HTML解析器，但在底层有一些神奇的东西。

在元素上设置属性(例如class)的方法: 1. 埃尔。className = string 2. el.setAttribute(‘类’,字符串) 3.el.attributes.setNamedItem(对象) 4. el.setAttributeNode(节点)

我做了一个简单的基准测试(这里)

似乎setAttributeNode比使用setAttribute快3倍。

所以如果性能是一个问题-使用“setAttributeNode”

这看起来像是使用setAttribute更好的一种情况:

高效的JavaScript

var posElem = document.getElementById('animation');
var newStyle = 'background: ' + newBack + ';' +
'color: ' + newColor + ';' +
    'border: ' + newBorder + ';';
if(typeof(posElem.style.cssText) != 'undefined') {
    posElem.style.cssText = newStyle;
} else {
    posElem.setAttribute('style', newStyle);
}

增加2个与.textContent和.innerHTML相关的点

<div id="mydiv"></div>


var elem = document.getElementById("mydiv");

elem.textContent = "hello"; // OK - Content has been updated
elem.setAttribute("textContent", "hello"); // NOT OK - You are trying to set
                                           // the attribute than it's content

elem.innerHTML = "world";   // OK - Content has been updated
elem.setAttribute("innerHTML", "world"); // NOT OK - You are trying to set
                                         // the attribute than it's content

来自Javascript: The Definitive Guide，它澄清了一些事情。它注意到HTML文档的HTMLElement对象定义了与所有标准HTML属性对应的JS属性。

因此，您只需要对非标准属性使用setAttribute。

例子:

node.className = 'test'; // works
node.frameborder = '0'; // doesn't work - non standard attribute
node.setAttribute('frameborder', '0'); // works

我发现需要使用setAttribute的一种情况是在更改ARIA属性时，因为没有相应的属性。例如

x.setAttribute('aria-label', 'Test');
x.getAttribute('aria-label');

没有x。arialabel之类的东西，所以你必须使用setAttribute。

编辑:x["aria-label"]不工作。你确实需要setAttribute。

x.getAttribute('aria-label')
null
x["aria-label"] = "Test"
"Test"
x.getAttribute('aria-label')
null
x.setAttribute('aria-label', 'Test2')
undefined
x["aria-label"]
"Test"
x.getAttribute('aria-label')
"Test2"