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Javascript modify css class

By | 08.10.2020

Yet another tutorial of javascript explaining very basic functionlity of it. Well in this you will learn how to change the class of any element dynamically on an event. I am using the onclick event which is fired when the div is clicked. I have associated a function changeClass when the div gets clicked.

The HTML code for the div would be.

How to Add/Remove CSS Classes Using JavaScript

I have defined two classes namely first,second to define the styles of the div. These classes get interchanged by simply clicking on the done.

This functionality is achieved by the javascript function. The two css classes look like :. Now we need to define the logic in javascript which let us interchange the two classes dynamically. All set all done. When you copy paste these block of codes in their respecting places, i. For those who do not want to copy the whole working code Click Here to unhide the code. I know this is just another tutorial you found online for creating horizontal menu on a self hosted wordpress blog Hi everyone, Yet another tutorial of javascript explaining very basic functionlity of it.

Hi i am the text just when the page loads with a default class. Share this post:. Add javascript function using css class Add append remove value in select html element using javascript What is self executing function in Javascript.

How TO - Add a Class

Read previous post: Create Horizontal Menu in WordPress I know this is just another tutorial you found online for creating horizontal menu on a self hosted wordpress blogApplying this function to a class will cause all items calling on the class to change to the updated style value. This function works even if there are multiple stylesheets referenced in the document. Function Name: changecss theClass,element,value. Example of output Assuming you have a stylesheet defining the "exampleA" and "exampleB" classes -- the following code creates the effect below :.

javascript modify css class

To use this function, copy this link and place it in the head of your HTML before any other JavaScript that may use it. This function was last updated on October 9, It has been tested and works in the following browsers:. Note that I have tested these browsers on Windows; this function works in Firefox in Linux as well. I assume that the latest Mac versions work the same.

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Vue JS 2 Tutorial #10 - Dynamic CSS Classes

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The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Modern browsers have added classList which provides methods to make it easier to manipulate classes without needing a library:.

Unfortunately, these do not work in Internet Explorer prior to v10, though there is a shim to add support for it to IE8 and IE9, available from this page. It is, though, getting more and more supported. The standard JavaScript way to select an element is using document. To remove a single class to an element, without affecting other potential classes, a simple regex replace is required:.

The g flag tells the replace to repeat as required, in case the class name has been added multiple times. The same regex used above for removing a class can also be used as a check as to whether a particular class exists:. Especially on larger applications, more maintainable code is achieved by separating HTML markup from JavaScript interaction logic. The first step to achieving this is by creating a function, and calling the function in the onclick attribute, for example:.

It is not required to have this code in script tags, this is simply for brevity of example, and including the JavaScript in a distinct file may be more appropriate. Note that the window.

The above code is all in standard JavaScript, however it is common practise to use either a framework or a library to simplify common tasks, as well as benefit from fixed bugs and edge cases that you might not think of when writing your code. Very roughly, a library is a set of tools designed for a specific task, whilst a framework generally contains multiple libraries and performs a complete set of duties.

The examples above have been reproduced below using jQueryprobably the most commonly used JavaScript library though there are others worth investigating too. In addition, jQuery provides a shortcut for adding a class if it doesn't apply, or removing a class that does:. In one of my old projects that did not use jQuery, I built the following functions for adding, removing and checking if element has class:.Get the latest tutorials on SysAdmin and open source topics.

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javascript modify css class

Become an author. This will give you a greater understanding of how to manipulate essential elements within the DOM. Until recently, a popular JavaScript library called jQuery was most often used to select and modify elements in the DOM. To review, document. Using a div with an id attribute in the example below, we can access that element either way. The querySelector method is more robust in that it can select an element on the page by any type of selector. 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. It is also possible to access a specific element with querySelectorAll the same way you would with an array — by using bracket notation. This is one of the most important differences to be aware of when progressing from jQuery to vanilla JavaScript. Many examples of modifying elements will not explain the process of applying those methods and properties to multiple elements. The properties and methods in this article will often be attached to event listeners in order to respond to clicks, hovers, or other triggers.

In these cases, you will need to use a standard for loop to iterate through the collection.

javascript modify css class

Attributes are values that contain additional information about HTML elements. Some of the most common HTML attributes are the src attribute of an img tag, the href of an a tag, classidand style. Custom elements that are not part of the HTML standard will be prepended with data. When you load the above HTML file into a modern web browser and open the built-in Developer Consoleyou should see something like this:. At this point, you will have removed the src attribute and value associated with imgbut you can reset that attribute and assign the value to an alternate image with img.

Finally, we can modify the attribute directly by assigning a new value to the attribute as a property of the element, setting the src back to the shark. The hasAttribute and getAttribute methods are usually used with conditional statementsand the setAttribute and removeAttribute methods are used to directly modify the DOM.Have you ever wished you could change the value of a Sass or Less variable after your page has loaded?

I have. I began by showing you how to define and use them and then offered some simple examples to make your code more readable and to help with contextual styling.

Last week I showed you how you can work with custom properties inside media queries. At the start of this series I mentioned that one of the major advantages of custom properties is their dynamic nature. Where preprocessor variables are turned into fixed values on compile, custom properties can change their values after a page has loaded. I touched on this dynamic ability last week when talking about media queries.

Today I want to continue and look at how we can make changes through user interaction and Javascript. Know that this will work on any pseudo class and not only :hover. I added some CSS to define a width and height and defined a custom property —background with a value of ccc.

I then set the background-color property using the var function and gave it a transition of 1s just because. To change the background color I redefined the custom property on the :hover pseudo class and assigned it a new value of cce. Realistically we could have done this without the use of custom properties by changing the background-color property directly or even with the use of preprocessor variables.

Maybe you want to change background color, text color, and various font properties. Where things get really interesting is when we use Javascript to change the values of custom properties. There are two things we need to be able to do to use Javascript with custom properties.

We need to know how to get the value of a custom property and also how to set a new value on a custom property. To read the value you use two Javascript functions, window. The former method will get every computed CSS property and value of every element and the latter method can be used to get the value of specific properties. If you work with Javascript, this is probably nothing new. The first line of Javascript below gets all the styles of document.

The second line gets the specific value for the —color custom property defined in :root and assigns that value to a new variable colorValue. In this case —color is the only property, but in practice there would likely be others. The variable colorValue should now hold a value of red, which is the value I initially set on —color in the CSS.

To proves this to yourself you can use the alert function to show the value on your screen. To set a new value on a custom property you use the style. Note that setProperty can take three parameters.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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The key is to define extra rules for additional classes and add these classes to the elements rather than to rewrite the rules for a given style rule. To access the style rules defined by style sheets, you access the document. Each entry in that collection will have a property either called cssRules or rules depending on the browser. Each of those will be a CSSRule instance.

You can change the rule by changing its cssText property. But again, that's probably not the best way to solve the problem. But it is the literal answer to your question. The best way to solve the problem is probably to have another class in your stylesheet that overrides the settings of the previous rule, and then to add that class either to the select elements or to the container of them.

So for instance, you could have the rules:. I'm accessing CSS classes directly to adjust the height of a bunch of divs simultaneously. This is how I'm doing it:. I only tried this on chrome for windows, good luck with other browsers. You can edit the style sheets, but I would think you would just create a new class instead.

If you really need to do it, try this. If that's the way you want to go, probably probably best to use some library, such as jquery. With it, you can do something like:. This shows both above approaches i. How are we doing? Please help us improve Stack Overflow. Take our short survey. Learn more. Asked 8 years, 2 months ago. Active 1 year, 1 month ago. Viewed 68k times. Is there a way to change an attribute of a CSS class using javascript? It looks simple but I can't find a way to do this Bedo Bedo 2 2 gold badges 11 11 silver badges 25 25 bronze badges.

Possible duplicate of stackoverflow. This one doesn't pre-suppose your use of that library. Crowder Feb 5 '12 at You may look at this site quirksmode.In this article we will look at how to dynamically update the styling applied to your elements by manipulating your CSS at runtime using JavaScript.

The browser provides an interface to interact with style sheets — in your JavaScript code you can access a list of your style sheets by using document. If your style elements have id attributes, you can reference them quickly with document. You can also add new style sheets to the page — you can use the document. This is useful when you want to give site visitors the option of changing your site styles dynamically, using some button controls perhaps.

Here is a quick example of how you could create a new style sheet:. Removing a style sheet is also very simple.

CSS Custom Properties—Dynamic Changes With And Without Javascript

First you must obtain the style sheet you wish to remove. You can do this by using document. To remove a style sheet you can use the DOM function parent. The accessing style sheets example demonstrates both accessing all styles sheets and adding and removing a new style sheet to the page.

The stylesheet object is available through JavaScript, and allows you to access information about a style sheet referenced from the current web page, such as if it is disabled, its location, and the list of CSS rules it contains. For a full list of the properties of the stylesheet object and many things besidescheck out the W3C Document Object Model Style Sheets documentation.

Thinking back to our unobtrusive JavaScript knowledgewe want the website functionality to still work for these users, but we might want to style the site differently for those users so that their user experience is still pleasant, even without the carousel. What you want is a style sheet that gets enabled only if JavaScript is enabled.

You are in luck — the DOM style sheet interface gives us access to the disabled attribute, which allows us to turn style sheets on or off. You can also use the style sheet properties to help differentiate between multiple style sheets on the page.

A better way, which allows you to reference both internal and external style sheets individually, is to use the title property. If you iterate through document. The following example shows how you can accomplish this iteration:.

For each stylesheet object retrieved from the styleSheets array you can access its title property to check if it has the title our code is looking for. You can see a functional example of this in the adding and removing rules examplewhich I will discuss in the next section. Switching between different style sheets based on user preference is a fairly common web site feature — using what we have discussed so far, you can set up multiple style sheets and enable only the ones that the current site visitor would want to view.

You can easily turn the CSS back on by setting disabled to false. Check out my style sheet properties example for a practical look at how to use this. Remember the theoretical showcase site we discussed above? On our webpage we show all the articles at once, but our user only wants to see the CSS articles.

How might we do this? Using CSS will actually be faster than traversing over all the elements. Our stylesheet object has two functions to help us with this problem. First is the insertRule function, which looks like this:. Here is how it might look.

In this example is a list of all the rules in a style sheet. Take a look at the adding and removing rules example. If you want to delete this rule, you can call the function stylesheet. In our article showcase example, we can create a rule that turns the display to none for all the HTML and JavaScript articles — check out the carousel example to see this in action. Note: IE does not implement rules according to the standard. Instead of the attribute cssRules it uses rules.

IE also uses removeRule instead of deleteRule and addRule selector, rule, index instead of insertRule. At this point you should understand how to edit style sheets connected to the page and create and modify the CSS rules within them.

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