Вопрос
I'm trying to create a menu where the currently selected (clicked) element has a different background color than the other elements (I'm trying to achieve this using JavaScript). I also use the CSS :hover pseudoclass to make the hovered element stand out by highlighting it. However, I have encountered a strange problem: when I set the background color of any element with JavaScript, its CSS hover behavior no longer works. That is, I can't highlight the element by hovering it anymore. I have checked that in Firefox and Chromium. This is the case for both jQuery and plain JavaScript.
The code is below. I have simplified it a lot to narrow down the problem. First try hovering any of the menu items, then click the "Set background color" link and hover one of the menu elements again. What I expect is the element getting red (#f00) when hovered, regardless of whether the "Set background color" button was clicked or not. For jsfiddle links, go to the bottom.
Vanilla JavaScript:
https://stackoverflow.com/questions/23312374
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Português
Russian<!doctype html>
<html>
<head>
<meta charset="utf-8">
<style>
p#links a {
display: inline-block;
width: 80px;
height: 22px;
line-height: 22px;
background-color: #00f;
color: #fff;
text-decoration: none;
text-align: center;
font-family: sans-serif;
}
p#links a:hover {
background-color: #f00;
}
</style>
<title>Background color</title>
</head>
<body>
<p id="links">
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
<a href="#">Link 4</a>
</p>
<a href="#" id="setbgcolor">Set background color</a>
<script>
document.getElementById('setbgcolor').onclick = function() {
var p = document.getElementById('links');
var elements = p.getElementsByTagName('a');
for (var i = 0; i < elements.length; i++)
elements[i].style.backgroundColor = '#ff0';
};
</script>
</body>
</html>
jQuery:
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<script src="jquery-1.11.0.js"></script>
<style>
p#links a {
display: inline-block;
width: 80px;
height: 22px;
line-height: 22px;
background-color: #00f;
color: #fff;
text-decoration: none;
text-align: center;
font-family: sans-serif;
}
p#links a:hover {
background-color: #f00;
}
</style>
<title>Background color</title>
</head>
<body>
<p id="links">
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
<a href="#">Link 4</a>
</p>
<a href="#" id="setbgcolor">Set background color</a>
<script>
$('a#setbgcolor').click(function() {
$('p#links a').css('background-color', '#ff0');
});
</script>
</body>
</html>
And here are jsfiddle.net links for the purpose of convenience:
Pure JavaScript: http://jsfiddle.net/5yQFM/1/
jQuery: http://jsfiddle.net/5yQFM/
Решение
The jQuery css() method maps onto the style property which maps onto the style attribute.
Rules inside a style attribute are more specific then rules in a stylesheet, so will always come after them in the cascade.
Instead of altering the CSS on the element directly, alter it by changing the classes the element belongs to and having a pre-prepared stylesheet.
Другие советы
you need to use !important on hover, basically it will increase its priority.
Try this,
p#links a:hover {
background-color: #f00 !important;
}
As Quentin said it looks like a dirty one, so in that situation we can make use of the class priority concepts.
HTML:
<a class='normal' href="#">Link 1</a>
<a class='normal' href="#">Link 1</a>
CSS:
.normal { background-color: blue; }
.abnormal{ background-color: yellow; }
.normal:hover { background-color: #f00; }
JS:
$('p#links a').attr('class', 'abnormal normal');
How about keeping the style in CSS and not in Javascript, by adding classes ?
so the line :
elements[i].style.backgroundColor = '#ff0';
Change to
elements[i].className = 'myClassForBackgrounds';
or in the jQ version
$('p#links a').css('background-color', '#ff0');
to :
$('p#links a').addClass('myClassForBackgrounds');
That way you can set your :hover as you would normally
#links a:hover, .myClassForBackgrounds:hover { background-color:#ff0; }
Just for a more simple answer, in able to just re-enable css rules just have it toggle between the color and "", so
document.getElementById("id").style.backgroundColor = "rgb(255, 125, 15)";
would be if the element wasn't already colored via javascript. Now, if your element was already colored the code would look like this:
document.getElementById("id").style.backgroundColor = "";
That re-enables CSS so then your selectors will work.
I encountered the same problem and solved it by doing this:
I set a onmouseover event to change the background color to what the hover color is.
I set a onmouseout event to change the background color to the default color.
This way I have set a hover event with pure javascript
