jQuery: How to check if two elements have the same class

问题

Is there a way to check if two elements have the same class name? My code looks like this...

<body class="foo bar cats">
<a href="#" class="foo">Link</a>
<a href="#" class="puppies">Link</a>

What I want to do is add another class to the foo link if it matches a class in the body. How would I check if one of the classes in my links matches a class in the body with jQuery?

回答1:

I'd suggest:

$('a').each(
    function() {
        var classes = this.classList;
        for (var i=0,len=classes.length; i<len; i++){
            if ($('body').hasClass(classes[i])){
                $(this).addClass('bodySharesClass');
            }
        }
    });

JS Fiddle demo.

Edited to try and account for Internet Explorer's inability to understand/use/implement .classList:

if (!document.createElement().classList){
    var useAttr = true;
}

$('a').each(
    function(i) {
        var classes = [];
        if (!useAttr){            
            classes = this.classList;
        }
        else {
            classes = $(this).attr('class');
        }
        for (var i=0,len=classes.length; i<len; i++){
            if ($('body').hasClass(classes[i])){
                $(this).addClass('bodySharesClass');
            }
        }
    });

JS Fiddle demo.

Edited because it appears my previous attempt, to account for IE, failed. Sigh. Still! This approach should work, albeit I can't test it, as I'm without both IE and Windows:

$('a').each(
    function(i) {
        var classes = this.className.split(/\s+/);
        for (var i=0,len=classes.length; i<len; i++){
            if ($('body').hasClass(classes[i])){
                $(this).addClass('bodySharesClass');
            }
        }
    });

JS Fiddle demo.

References:

classList.
hasClass().

回答2:

ok, assuming I understand you correctly, you can do something like this...

var link = $(".foo");//or select your link another way
var linkClass = link.attr("class");
if($("body").hasClass(linkClass)){
   //link has matching class
   link.addClass("newClass");
}

As you can see I have used the hasClass() JQuery function to check if the body tab has the matching class.

If your link will potentially have more than one class name you can do it like this...

var link = $(".foo");//or select your link another way
var linkClass = link.attr("class");
var classList = linkClass.split(/\s+/);

var matchFound = false;

for(var i = 0; i < classList.length; i++){
    if($("body").hasClass(classList[i])){
       //link has matching class
       matchFound = true;
    }
}

if(matchFound){
    link.addClass("newClass");
}

Also, if you want to process all your links at the same time you could wrap it all in a JQuery each() and change the first line like so...

$("a").each(function(index){
   var link = $(this);

   //the rest of the above code here
});

回答3:

$('a').hasClass('foo').addClass('whatever');

回答4:

using jquery hasClass() method will lead you to a solution

回答5:

Here is one suggestion, there might be others (that are better) as well :)

$(document).ready(function() {
    var $foo = $('.foo'); // select the foo link
    if ($(body).hasClass($foo.attr('class'))) {
        $foo.addClass('anotherClass');
    }
});

回答6:

var body_classes =$('body').attr('class').split(/\s+/);
var foo_link = $('a.foo');
$.each(body_classes, function(index, item){
    if (foo_link.hasClass(item)) {
       foo_link.addClass('class_you_want_to_add');
       return false; 
    }
});

来源：https://stackoverflow.com/questions/9603814/jquery-how-to-check-if-two-elements-have-the-same-class

标签

javascript

jquery

html

detection