使用纯JavaScript(不是jQuery)，是否有任何方法来检查元素是否包含类?
目前，我正在这样做:
var test = document.getElementById("test");
var testClass = test.className;
switch (testClass) {
例“class1”:
测试。innerHTML = "我有class1";
打破;
例“class2”:
测试。innerHTML = "I have class2";
打破;
例“class3”:
测试。innerHTML = "I have class3";
打破;
“一年级”情况:
测试。innerHTML = "I have class4";
打破;
默认值:
测试。innerHTML = "";
｝
<div id="test" class="class1"></div>
问题是，如果我把HTML改成这个…
<div id="test" class="class1 class5"></div>
.．.不再有一个精确的匹配，所以我得到的默认输出为nothing("")。但我仍然希望输出为I have class1，因为<div>仍然包含。class1类。
Felix's trick of adding spaces to flank the className and the string you're searching for is the right approach to determining whether the elements has the class or not.
To have different behaviour according to the class, you may use function references, or functions, within a map:
function fn1(element){ /* code for element with class1 */ }
function fn2(element){ /* code for element with class2 */ }
function fn2(element){ /* code for element with class3 */ }
var fns={'class1': fn1, 'class2': fn2, 'class3': fn3};
for(var i in fns) {
if(hasClass(test, i)) {
fns[i](test);
}
}
for(var i in fns) iterates through the keys within the fns map.
Having no break after fnsi allows the code to be executed whenever there is a match - so that if the element has, f.i., class1 and class2, both fn1 and fn2 will be executed.
The advantage of this approach is that the code to execute for each class is arbitrary, like the one in the switch statement; in your example all the cases performed a similar operation, but tomorrow you may need to do different things for each.
You may simulate the default case by having a status variable telling whether a match was found in the loop or not.
在哪个元素中当前是类的。酒吧”?这里有另一个解决方案，但取决于你。
var reg = /Image/g, // regexp for an image element
query = document.querySelector('.bar'); // returns [object HTMLImageElement]
query += this.toString(); // turns object into a string
if (query.match(reg)) { // checks if it matches
alert('the class .bar is attached to the following Element:\n' + query);
}
jsfiddle演示
当然，这只是查找一个简单的元素<img>(/Image/g)，但您可以将所有元素放在一个数组中，如<li> is / li /g， <ul> = / ul /g等。
