javascript 元素没有方法hasAttribute，为什么？
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Element has no method hasAttribute, Why?
提问by jenswirf
I'm trying to iterate "up" through the DOM nodes from a given element to get the first parent element which has the attribute 'animated'.
我正在尝试从给定元素“向上”遍历 DOM 节点，以获取具有“动画”属性的第一个父元素。
var el = evt.target;
console.log(el);
while (!el.hasAttribute('animated'))
{ el = el.parentNode; }
return el;
console.log(el);
Throws error:
抛出错误：
>>>Uncaught TypeError: Object #<HTMLDocument> has no method 'hasAttribute'
>>>Uncaught TypeError: Object #<HTMLDocument> has no method 'hasAttribute'
How is this possible? I've clearly declared the variable eland the first log is correct .
这怎么可能？我已经清楚地声明了变量el并且第一个日志是正确的。
回答by Quentin
The documentobject:
该document对象：
- Is a node
- Is the
parentNodeof the root element (if you were using HTML that would be the<html>element) - Is not an element.
- 是一个节点
- 是
parentNode根元素的（如果您使用的是 HTML<html>元素） - 不是元素。
Only elements have attributes, so only element objects have a hasAttributemethod.
只有元素才有属性，所以只有元素对象才有hasAttribute方法。
You need to stop testing when you reach the document object (or when you aren't testing an element any longer).
当您到达文档对象时（或不再测试元素时），您需要停止测试。
while (
el.nodeType === 1 &&
(!el.hasAttribute('animated'))
) {
回答by Farhan Ahmad
var el = evt.target
is a documentobject and therefore does not have a hasAttributeattribute.
var el = evt.target
是一个document对象，因此没有hasAttribute属性。
回答by jfriend00
You could also make it into a function that returns either nullor the ancestor node that has that attribute:
您还可以将其变成一个函数，该函数返回null具有该属性的祖先节点：
function findNodeWithAttribute(el, attr) {
while (true) {
if (!el || !el.hasAttribute) {
return null;
} else if (el.hasAttribute(attr)) {
return el;
}
el = el.parentNode;
}
}
