How to select element by 'role' attribute and filter by class with vanilla JS?

问题

Markup:

<ul>
  <li role="presentation" class="active">
    <a href="#1" aria-controls="1" role="tab">How to Install for iPad</a>
  </li>
  <li role="presentation">
    <a href="#2" aria-controls="2" role="tab">How to Install for Mac</a>
  </li>
  <li role="presentation">
    <a href="#3" aria-controls="3" role="tab">How to Install for PC</a>
  </li>
</ul>

When I use document.querySelectorAll('[role="presentation"]'); the result is array [li.active,li,li]

How can I remove .active class and attach it to any other of these li with plain JS w/o JQuery the more simplest way?

回答1:

Try this:

// remove active class from all elements
document.querySelectorAll('[role="presentation"]').forEach(function (el){
el.classList.remove("active");
});

// add class 'active' to last element
document.querySelectorAll('[role="presentation"]:last-of-type')[0].classList.add("active")

Notes:

'classList' will not work in IE9;
I think you have to modify adding class row, depending on your needs.

回答2:

You can try something like this:

var ele = document.querySelectorAll('[role="presentation"]');
ele[0].classList.remove("active"); //Remove active class for first element
ele[ele.length- 1].classList.add("active"); //Apply active class for last element
console.log(ele)

回答3:

var eleLi = document.querySelectorAll('[role="presentation"]');  
for (var i = 0; i < eleLi.length; i++) {
    //remove class active
    eleLi[i].classList.remove('active');
}

//x is an index of li that you want to add the class. Such as 0,1,2
var x = eleLi.length - 1;

//add class active
eleLi[x].classList.add('active');

来源：https://stackoverflow.com/questions/46648761/how-to-select-element-by-role-attribute-and-filter-by-class-with-vanilla-js

标签

javascript

css-selectors