How to change the style of elements with same class name

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Using javascript, I want to change the style of class .s into

.s {
  display: block;
}

Why this cannot work:

document.getElementsByClassName('s').style.display='block';

document.getElementsByClassName: returns a set of elements which have all the given class names.

You may have multiple elements with this class name. so you need to provide index like

document.getElementsByClassName('s')[0].style.display='block';

Inorder to apply for style for all elements with same class name:

var ele = document.getElementsByClassName('s');
for (var i = 0; i < ele.length; i++ ) {
    ele[i].style.display = "block";
}

How To Modify Attributes, Classes, and Styles in the DOM , CSS classes are used to apply styles to multiple elements, unlike IDs which can only exist once per page. In JavaScript, we have the className� Example. Toggle between class names on different scroll positions - When the user scrolls down 50 pixels from the top, the class name "test" will be added to an element (and removed when scrolled up again).

As getElementsByClassName returns an array you need to make a for loop over all found elements:

var elements = document.getElementsByClassName('s');
for (var i = 0; i < elements.length; i++) {
    elements[i].style.display = "block";
}

element.getElementsByClassName, Syntax. element.getElementsByClassName(classname) Change the background color of the second element with class="child" inside of a <div> element: getElementsByClassName("child"); var i; for (i = 0; i < y.length; i++) { y[ i].style. The .class selector selects elements with a specific class attribute. To select elements with a specific class, write a period (.) character, followed by the name of the class. You can also specify that only specific HTML elements should be affected by a class. To do this, start with the element name, then write the period (.) character

var sCls = document.getElementsByClassName('s');
for(var i in sCls) {
    sCls[i].style.display='block';
}

this may work!

Little CSS Stuff Newcomers Get Confused About, It's the little fundamental stuff, like tiny differences in syntax that change The second one will only select paragraph elements with that class name. div { font- family: Sans-Serif; font-size: 18px; font-weight: bold; font-style: italic; color: And then they apply to the same element, the selector later in the CSS will always win. The class name is used as a selector in HTML which helps to give some value to the element attributes. The document.getElementById() method is used to return the element in the document with the “id” attribute and the “className” attribute can be used to change/append the class of the element.

Element.getElementsByClassName(), names: A DOMString containing one or more class names to match on, if an existing element that doesn't match names has its set of classes� However, when accessing multiple elements by a common selector, such as a specific class, we have to loop through all the elements in the list. In the code below, we have two div elements with a common class value.

Styles and classes, JavaScript can modify both classes and style properties. of an element dynamically and want to set them from JavaScript, like this: So for classes the similar-looking property "className" was Setting elem.style.width="100px" works the same as if we had in the attribute style a string width:100px . The standard JavaScript way to select an element is using document.getElementById("Id"), this is what the following examples use but you can obtain elements in other ways. To change all classes for an element and to replace all the existing classes with one or more new classes, set the className attribute like this:

Dynamic style - manipulating CSS with JavaScript, It uses the same kind of technique that we've already seen, but there are a If your style elements have id attributes, you can reference them quickly with document By calling element.style.color = "red"; you can apply the style change You can append strings to className if you want to add a class to an element, or you� 1. Put the class name at the lowest possible level. It impacts how classes will be named. Always use the class name directly on the HTML element you want to style, even if seems to cost an extra effort. Check the article of Chris Coyer below if it is not clear why. Example :

Comments
  • Why not create a class for the new styles and append this new class to all of the matching classes?
  • @JoshSmickus, those lines are used in the response code of a checkbox. I want to use that checkbox to control if some elements should be shown.
  • So, you could write: var elems = document.getElementsByClassName('s'); for(var i = 0; i < elems.length; i++) { elems[i].className += " new-class"; } Then define new-class with appropriate styles
  • @JoshSmickus, What I really want to say is: because of "...", I don't think it is appropriate to "create a class for the new style and ..."
  • What? :S I don't get what you mean?
  • Is there a easy way to change all the items at the same time.
  • @FANGYishu go for looping.
  • It would be nice if we can change the style sheet directly, not the style of just each elements.
  • @FANGYishu if you're trying to change the css rules then take a look at T.J Crowder's answer