HTML-Attribute. You could write a function that runs getElementsByTagName('*'), and returns only those elements with a "data-foo" attribute: function getAllElementsWithAttribute(attribute) { var matchingElements = []; var allElements = document.getElementsByTagName('*'); for (var i = 0, n = allElements.length; i < n; i++) { if (allElements[i].getAttribute(attribute) !== null) { // Element exists with attribute. data-toggle=”tab”. Especially with complex systems where backend devs build the JS for callbacks etc. Transport. 2. Every HTML element may have any number of custom data attributes specified, with any value. The trick is to rely on classes for DOM node selection in JavaScript to gain performance but to use a naming convention and strictly separate styling classes from logic classes. Trying to decouple CSS and JS by using data attributes is not a new thing. We can either use dataset property to get access to the data attributes or use .getAttribute() method to select them by specifically typing their names. I disagree … “what bothers me more is the fact that the data attribute, by definition, is just not intended to be used that way” – true but true for css classes as well. Performance Example: Let’s assume that the integration of motorcycles would require some CSS refactoring. In JavaScript The property name of a custom data attribute is the same as the HTML attribute without the data-prefix, and removes single dashes (-) for when to capitalize the property’s “camelCased” name. I am not yet sure what exactly you are trying to do on your page. Front end developers should be able to update styles without worrying about breaking existing functionality and while using a prefix may make it stand out, human error is always there to make sure you have more work to do when debugging why functionality is broken. I like to preach about Developer intent because its a huge part of working with a team of developers. Example: Javascript spiegelt die meisten Standard-Attribute von HTML-Tags beim Laden der Seite als Eigensch getAttribute oder (ab IE11) mit dataset.status behandelt. I don’t need to decipher all styles to understand whats going on here. It is also a frequent occurrence for 3rd party javascript to arbitrarily mutate, strip, or alter classes on elements when they have styling considerations, which makes classes extremely likely to collide, not be present as expected, or otherwise cause frequent mishaps and collisions with 3rd party libraries. If the attribute exists on the element, the getAttribute() returns a string that represents the value of the attribute. Example: As we can see, both CSS and JS use the same class to get their job done. Through this change both CSS and JS won’t work anymore. and so on…. An element's data-* attributes are retrieved the first time the data () method is invoked upon it, and then are no longer accessed or mutated (all values are stored internally by jQuery). 3. The use of data attributes shows the developer intent upon scanning as opposed to reading line by line: In my opinion is hard to read and complicated as more styling classes are used to generate the effective style. Date: 2010-10-24. This is the most expensive thing you can do in javascript apart from modifying its DOM. Data-Attribute werden mit setAttribute bzw. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. With the introduction of HTML5, JavaScript developers have been blessed with a new customizable and highly flexible HTML tag attribute: the data attribute. var $rentalList = $(“.rentals”); This will search the full DOM 3 times which is very expensive ( SLOW ) Depending on how large and deep your DOM is performance may vary. Returns null if not found. Tip: Use the getAttributeNode () method if you want to … In case the attribute does not exist, the getAttribute() returns null. classes are specifically used for styling and data attribute specifically tied to javascript functionality. Using this attribute to store small chunks of arbitrary data, developers are able to avoid unneccessary AJAX calls and enhance user experience. I much prefer to use data-attibs for JS selectors, as it does a couple of things. To be more specific, attributes is a key/value pair of strings that represents any information regarding that attribute. The advent of HTML5 introduced a new attribute known as 'data'. The following syntax to represents the getElementsByName () method: 1 let elements = document.getElementsByName (name); If the next developer does not know the intent or needs to read all the code previously written to understand whats going on then there is a lack of efficiency when working with Large teams of developers. Second, it says “intended to store custom data”, everything in the DOM is data and data can be used for many things, included finding elements, just like class and id are data that is used to find and select elements. Here, I’ll show you how using a simple jQuery method, you can find elements by its data attribute value. In vanilla JavaScript setting a data attribute of an element is done with the generic setAttribute() method. HTML5 data attributes allow developers to add data to an element. It always bugged me that dependencies between styling (CSS) and logic (JS) arise through shared classes. Now, how do you extract and use the data that are associated with the elements? Hi, I was working with data- attribute and I was searching what is the best way of select html with this kind of selector. var $carsList = $(“.cars”); Well, for one there are performance issues. The NodeList object represents a collection of nodes. Period. In this specific example although, there is the drawback of having a too specific name for the JS module and that just feels wrong. Etwas Plus für getAttribute Definition and Usage. The JavaScript getElementByName () is a dom method to allows you to select an element by its name. Thank you Chris Rivera, I concur, this is exactly what I was thinking reading this article. On the website of a car rental company we find a list of available cars. The setAttribute () method adds the specified attribute to an element, and gives it the specified value. The index starts at 0. How to append an element after an element using jQuery? Attribute von HTML-Tags werden in Javascript als Objekte mit Eigenschaften und Methoden aufgefasst. Any attribute on any element whose attribute name starts with data- is a data attribute. What is discouraged is making upyour own attributes, or repurposing existing attributes for unrelated functionality. The name of the attribute you want to get the value from. Using data attributes does not prevent multiple such third party libraries from interfering with each other, and such occurrences indicate a poorly written library. There is many things wrong with this idea the biggest reason is that css is meant for styling purposes. I think he is right. The next example locates the element and reads the data attribute data-content2. Only that way we can assure that CSS and JS are decoupled and less of a PITA when it comes to refactoring. This way we can use it throughout the whole site. A more scalable and robust module could look like this: The names of the data attributes are no more associated to the content within the module. Examples might be simplified to improve reading and learning. The developer renames the HTML class from cars to vehicles. intuio GmbH, use data attributes to find HTML elements with JS, Roy Tomeij analyzes the exact differences in performance, Don’t use class names to find HTML elements with JS, Follow-up: Don’t use class names to find HTML elements with JS, About HTML semantics and front-end architecture, https://roytomeij.com/en/dont-use-class-names-to-find-html-elements-with-js/. var list = $(“.cars”); javascript - tag - jquery get element by data attribute Holen Sie sich alle Attribute eines HTML-Elements mit Javascript/jQuery (8) Verwenden Sie.slice, um die attributesin Array zu konvertieren Die attributesvon DOM-Knoten ist eine NamedNodeMap, bei der es sich um ein Array-ähnliches Objekt handelt. […]. The nodes can be accessed by index numbers. The data attribute would then hold some metadata, i. e. duration, bitrate, codec… you get the point. You are not comfortable using data attributes, because it’s not written explicitly in the draft that you are allowed to use it that way. When you see data attributes you know its tied to js functionality no guessing work here. Roy’s article link was broken. Data Attribute is the slowest javascript selector since there are more data attributes in a DOM than ids and classes, so for performance reasons we cache the selector for future reference as context. Here's an example for setting and retrieving the attribute "data-foo": // setting data-foo var el = document.querySelector('div'); el.setAttribute('data-foo', … This is all very basic stuff but it clearly demonstrates one way the data attribute can and should be used. var $module = $(“[data-module=Cars]”); Just by looking at this code it would be easy to assume that data-module=Cars is related to javascript module called Cars. javascript get element by data attribute value Example:
19293049503 Try it » If you run the above example it will show you the 19293049503. Perhaps something to think about. I think that is worth the extra tenth of a second it takes to run one querySelectorAll statement, as it insures that the ongoing performance of the page is not disrupted for the sake of shaving microseconds off of load time. var $truckList = $(“.trucks”); The problem with using classes for id’s is that classes have the ‘side effect’ of well being classes – they style their elements. Nothing more, nothing less. The site taking some 400ms extra to finish loading or finish an operation is far from being an important issue, while your solution throws readability out of the window, specially in elements that have several classes or maybe several custom attributes. There’s a clear distinction between what is JS and what is CSS and neither code bases pollute each other. elem.value würde bei einem div-Tag undefined zurückgeben, weil value kein Attribut des div-Tags ist. Additionally, if it’s unlikely that some other library collides with your selected unique data attribute, it would probably be equally unlikely if you picked a “likely-to-be-unique” prefix for all your own classes. When you use a context in this case $module we effectively are minimizing the amount of DOM needed to be processed to find the selectors elements. 1. data-Attribute sind Zeichenketten oder Strings, die alles speichern, was in einem String stehen kann – ähnlich wie JSON. Maybe try http://codepen.io/pen and share the link with us. jQuery provides a function called data(). Makes for a bit easier debugging too since you tell, at a glance, if a class is being added or was already there. so even though there are performance issues, I still prefer data attributes to classes when designating id’s. First, select the element which is having data attributes. This function makes it very easy to access an set data attribute values. Ironically the article suggests we are using data-attributes wrong, but isn’t using .js-trigger class selectors equally goes against the grain as what’s it’s intended purpose as for? I use prefixes: ‘trigger-‘ for pre-existing classes and ‘js-‘ for classes added by js. Thanks. data-toggle=”collapse” Using this attribute to store small chunks of arbitrary data, developers are able to avoid unneccessary AJAX calls and enhance user experience. Since we have saved $module selector we can avoid the performance pitfall of using data attributes to query the full DOM by searching thru a specific context of the DOM. here’s a jsperf: http://jsperf.com/generictestjsperf. If the specified attribute already exists, only the value is set/changed. var $rentalList = $module.find(“[data-rental]”); How this is faster: Wenn setAttribute auf einem HTML-Element in einem HTML-Dokument aufgerufen wird, wird der Name des Attributes in Kleinbuchstaben umgewandelt.. Wenn das angegebene Attribut bereits existiert, ersetzt setAttribute den alten Wert. If n… Note that you can use the hasAttribute() method to check if the attribute exists on the element before getting its value. The most compelling reason is that HTML is a living language and just because attributes and values that d… The class cars for example can be used in CSS as well as in JS. That’s going to be our invisible, low priority data. If the selector is not valid CSS syntax, the method will raise a SyntaxErrorexception. var $cars = $vehicles.find(“.cars”); Integer oder Float) muss vom Javascript durchgeführt werden. In addition to the information below, you'll find a how-to guide for using HTML data attributes in our article Using data attributes. You can use the CSS attribute selectors to find an HTML element based on its data-attribute value using jQuery. Custom data attributes are intended to store custom data private to the page or application, for which there are no more appropriate attributes or elements. Information contained in the data attribute can only become visible through JavaScript or through the CSS content property. Roy Tomeij adviced to use data attributes to find HTML elements with JS before and I have seen others do the same. Selecting the Single element. data-status ist ein data-Attribut, das sich speziell an Javascript richtet: Javascript data-attribute. Die Konvertierung in andere Datentypen (z.z. Every time you see $({*}), this will look thru the whole DOM to find the element you are looking for.