![](/img/trans.png)
[英]On click add class to element with certain class and remove it from all other elements with same class
[英]Add a class to target and remove class from other elements with the same class name
我试图找出一种方法,可以将一个类添加到目标元素,同时从另一个具有相同类的元素中删除一个类。
到目前为止,我已经有了这段代码。 该代码可以按需工作,但是它说该对象未定义,我对此感到困惑。 有没有更好的方法来做我想做的事情?
它必须使用纯香草javascript。 在此先感谢HTML
<ul class="number-container"><li class="number-item"><span class="number number-active" data-number="zero"></span></li>
<li class="number-item"><span class="number" data-number="one">1</span></li>
<li class="number-item"><span class="number" data-number="two">2</span></li>
<li class="number-item"><span class="number" data-number="three">3</span></li>
<li class="number-item"><span class="number" data-number="four">4</span></li>
<li class="number-item"><span class="number" data-number="five">5</span></li>
<li class="number-item"><span class="number" data-number="six">6</span></li>
<li class="number-item"><span class="number" data-number="seven">7</span></li>
<li class="number-item"><span class="number" data-number="eight">8</span></li>
<li class="number-item"><span class="number" data-number="nine"></span></li>
</ul>
使用Javascript
// store elements in dom
var numberButtons = document.querySelectorAll(".number");
// loop to add event listener to each button
for (var i = 0; i < numberButtons.length; i++) {
// add click event listener
numberButtons[i].addEventListener("click", changeButton);
}
function changeButton(e) {
// get dataset value
var target = e.target;
var targetDataset = e.currentTarget.dataset.number;
for (var i = 0; i <= numberButtons.length; i++) {
numberButtons[i].classList.remove("number-active");
if (targetDataset === "zero") {
target.classList.add("number-active");
} else if (targetDataset === "one") {
target.classList.add("number-active");
} else if (targetDataset === "two") {
target.classList.add("number-active");
} else if (targetDataset === "three") {
target.classList.add("number-active");
} else if (targetDataset === "four") {
target.classList.add("number-active");
} else if (targetDataset === "five") {
target.classList.add("number-active");
} else if (targetDataset === "six") {
target.classList.add("number-active");
} else if (targetDataset === "seven") {
target.classList.add("number-active");
} else if (targetDataset === "eight") {
target.classList.add("number-active");
} else if (targetDataset === "nine") {
target.classList.add("number-active");
}
}
}
编辑:您的最初错误是for (var i = 0; i <= numberButtons.length; i++) {
,您需要一个<
,而不是一个<=
。
您需要data-number
属性做什么? 在target
您已经具有选定的元素。 您的脚本可以简化:
var numberButtons = document.getElementsByClassName("number");
for (var i = 0; i < numberButtons.length; i++) {
numberButtons[i].addEventListener("click", changeButton);
}
function changeButton(e) {
var oldActive = document.getElementsByClassName("number-active");
// depending on your usage you could also replace oldActive by numberButtons
for (var i = 0; i < oldActive.length; i++) {
oldActive[i].classList.remove("number-active");
}
e.target.classList.add("number-active");
}
我将示例上传到Codepen 。
一种有效的方法是使用JavaScript保持某些先前状态。 更进一步,以下代码通过使用闭包隐藏状态。
function selector(token) {
var last;
return function(element) {
if (element !== last) {
if (last) last.classList.remove(token);
element.classList.add(token);
last = element;
}
}
}
var select = selector('number-active');
document.querySelector('ul').addEventListener('click', function(e) {
var target = e.target;
if (target.classList.contains('number')) {
select(target);
}
});
https://jsfiddle.net/7qdqxzrs/
undefined
错误来自for
语句的条件检入。 ES6具有for..of
,这可以使事情变得更容易。
for (var numberButton of numberButtons) {...}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.